Project Evo X GSR- Testing the Greddy RS  Catback Exhaust System

Project Evo X GSR- Testing the Greddy RS Catback Exhaust System

By Mike Kojima
In our last edition of Project Evo X GSR, we tested the K&N Typhoon Cold Air Intake with excellent results. Since the next logical choice in the path to modding our car is to free up the exhaust, we went to our friends at Greddy to get one of their RS exhaust systems to evaluate. The Greddy RS is a new line of exhausts that are constructed much like their race only systems. The main differences in the RS exhausts are that they allow the use of the stock catalytic converter and do not feature exotic titanium in their construction.
Project Evo X GSR- Testing the Greddy RS  Catback Exhaust System
Chris Marion removes the stock Evo X exhaust main muffler.  We were able to switch the exhaust in a few minutes at home.
The Evo X has a pretty decent stock exhaust. With twin outlets and a straight design with minimal bends, the stock exhaust is pretty free flowing. However, it is very heavy. The stock muffler is huge and constructed of very thick gauge metal. We were curious if the Greddy exhaust could out power it without a downpipe and a less restrictive turbo outlet.
Project Evo X GSR- Testing the Greddy RS  Catback Exhaust System
Chris removes the cat to muffler pipe.
One thing for sure was that the Greddy exhaust was much lighter, we estimate that the Greddy system saved about 30 lbs over stock. The Greddy RS exhaust is made of fairly thin wall 304 stainless steel, a high quality rust resistant grade of stainless. The tubing diameter is a generous 80mm which should be enough to support some pretty aggressive horsepower goals.
Project Evo X GSR- Testing the Greddy RS  Catback Exhaust System

The Greddy RS exhaust is an aggressive exhaust much like the race only Greddy titanium exhaust system.  It is designed to be lightweight with a minimum of power robbing bends.  Unlike the race system, the RS can be used with the stock cat.

The RS has two mufflers. The main muffler has an oval polished 304 stainless case and a perforated core inner main tube with a 130mm diameter tip. Perforated cores provide the lowest possible backpressure as the perforations contribute minimally to turbulence. The core tube is wrapped with a stainless steel wool which provides mechanical strength against exhaust pulses and acts like a buffer to prevent the exhaust from blowing the packing out like common fiberglass packing will.
Project Evo X GSR- Testing the Greddy RS  Catback Exhaust System
The stock dual outlet muffler is pretty low backpressure but is heavy, really heavy.  The RS exhaust saves a lot of weight at the rear of the car.  In this picture you can compare the stock muffler vs the RS muffler.


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Thursday, January 05, 2012 6:30 AM
Boo. Fart cans aren't cool anymore. And on a car with stock dual exhaust tips, it just looks weird to me. I'm sure the power gains are there, but aesthetically it doesn't work for me. Maybe I'm getting old :(
Thursday, January 05, 2012 6:50 AM
I dunno jeffball... I've never really liked the idea of an I4 engine coming with a dual outlet exhaust seeing as that's just cosmetics anyways. In this case it's not even dual mufflers but just dual outlets so why bother?
Mike Kojima
Mike Kojimalink
Thursday, January 05, 2012 6:54 AM
Plus getting rid of about 30 lbs back there is useful.
Thursday, January 05, 2012 7:12 AM
Yes, dual tips/mufflers are lame on a car with a single exhaust.
Naji Dahi
Naji Dahilink
Thursday, January 05, 2012 10:38 AM
I agree with those that say that a dual tip exhaust is silly on an I4 engine. It is just for looks and adds a lot of extra weight.

On a different note, rumor has it that the 2011 Evo X has a better flowing stock exhaust than the 2008-2010. It is allegedly so good that an aftermarket exhaust is not needed. Simply install a test pipe and you are done.

I would love to do a back to back test between a 2010 exhaust and a 2011 exhaust to see if there is any truth to the rumor.
Thursday, January 05, 2012 11:13 AM
Dual tips/mufflers have a purpose. On the S2k, there are two separate mufflers which serves the purpose of adequately muffling the noise while minimizing back pressure. On the Evo X, the single super-big muffler has dual outlets instead of a single huge outlet. Same flow, less huge tip. Your average customer doesn't care for a huge tip; I don't even.

As for test pipes, I hate them. They are excusable for a track-only car, but even then I still hate them. Modern 3-way cats have a conversion efficiency of turning harmful emissions into nonharmful stuff of up to 90%. So by running a test pipe on a street car, the car is now dumping 10x the emissions. The only power gains for a test pipe are basically at WOT, and that's basically never on the street, so cars with test pipes are just polluting for no reason.

Even many racing series requires cats now such as the BTCC and WTCC, and various rally series in Europe. The last track day I was at, I was behind a few cars with test pipes and I had a hard time breathing. Did I mention that I hate them?
Naji Dahi
Naji Dahilink
Thursday, January 05, 2012 11:30 AM
It is my understanding that unlike NA cars that can benefit from exhaust pipe sizing to improve exhaust gas scavenging, turbo cars hate any exhaust restrictions. I have tested turbo cars back to back with a dump pipe (open wastegate pipte that dumps in the open) and those with a regular 3 inch exhaust and we gained 25 hp. This is just from the dump pipe. I have also tested back to back on my own Evo 9 test pipe vs. high flow cat and found gains of 17 hp.

I do agree that test pipes pollute, but that does not mean that turbo cars do not like them. Infact, my testing indicates that turbo cars love them.
Mike Kojima
Mike Kojimalink
Thursday, January 05, 2012 12:00 PM
You don't care for a single big tip, not your average consumer. If you made an exhaust with a small flat black tip, my gut feel is that it would not sell well. My STI has a huge polished stainless tip bone stock....
Thursday, January 05, 2012 12:20 PM
Maybe my comment was taken out of context. I loved my Apexi N1 on my 1G Talon. But on a car with a rear bumper meant for two tips, it just doesn't look right. Just like running a single muffler on a Z would look weird.
The weight loss is nice. The flow is great. I just think that two tips look nicer in this instance.
And my girl likes a big tip, so at least someone likes it ;)
Thursday, January 05, 2012 12:47 PM
I see lots of tests on adding intake and exhuast and giving HP increases to each. I do not know of anyone who would only do one of those mods and not the other. I always wonder which is fair to test first. I would like to see a test where you did the intake and got X HP for a gain, then did the exhuast for gain of Y HP. Then put back the old intake and see if you lost only X HP. I would expect you would lose X and some portion of Y. Am I making any sense?
Thursday, January 05, 2012 12:59 PM
Naji, I never said test pipes don't make improve peak power ;) Turbo cars are simple, reducing backpressure frees up power and that's what a test pipe and open dump do.

My contention is that for a street car, where even if you're driving like a jackass, you're only seeing the benefit of the test pipe ~2%-3% of the time (rough estimate of how long you can got WOT on the street in daily driving without getting arrested). For the other 97%-98% of the time, the car is polluting 10X more.

A track car where you're WOT 80%+ of the time and actually racing as opposed to just driving fast justifies a test pipe. Also, conversion efficiency of a cat goes down at WOT. I'd personally still like to see every track car with a high flow cat at least, and that's the trend in professional racing now. It especially makes sense in series where there are power restrictions.
Thursday, January 05, 2012 1:42 PM
Aesthetically I like better a single muffler with a single tip (I like simplicity), and all these new cars that come with dual tips are just non-sense to me. Even the newer Miata have a dual tip.
Anyway, as long as the aftermarket product make power, that's where I'm leaning toward to.
I personally could care less if the tip is shiny chrome or black (actually, to tell you the truth, the more subtle the look, the better). Chrome-fat tips are for the young crowds IMO.....I have a Apexi Noir exhaust on my Civic and love the stealthy-look. Again, if it makes power, I'm all for it.

Changing subject; regarding a test-pipe and its benefit. Doesn't a cat-less exhaust help to spool up the turbo quicker? Because if that's the case (and I owned a turbo car), I honestly could care less about tree-huggers and EPA's.
There are far more polluting cars out these than a Lancer EVO.
Thursday, January 05, 2012 3:56 PM
I prefer a single muffler but I can't stand the cut out for 2 but only one tip... if someone made a decently priced diffuser for the X with a single cut out I'd be selling my current T1R...

the problem with cats on tracked evo's is that they melt. Before buying my test pipe I was dead set on a hi flow cat, but after doing some research I found the 9 out of 10 people who track their evo's with one have it melt on them in 1-2 events. the really good cats the don't melt with track use are dedicated motorsports cats that most consumers don't even have access to, not to mentions they cost around $800 (last I heard)

Naji Dahi
I have a 2011, the only difference in the exhaust is one of the baffles is removed in the muffler. its the same exact mod Works does:
I'd let you test it buy I gave it to some guy that was at the shop when I installed by T1R and I think he sold it on craigslist...

for anyone thats interested, here's a vid of my stock 2011 exhaust
Thursday, January 05, 2012 3:58 PM
are those RT615's or RT615K's? stock size? how do they compare to the stocker Yoko's? I'm particularly interested in braking performance...
Thursday, January 05, 2012 4:13 PM
I know I can't shut up... but I thought the MotoIQ Legit certification was for products that really stood out from the rest of the market... "cutting edge, works well, makes sense, bests others in performance"

I can see works well and makes sense, but its an average single catback for the Evo X, nothing cutting edge about it.. it doesn't outperform your average single catback either...

Not that I'm saying that this exhaust sucks, I just thought the Legit stamp was for something that really is better than the rest.
Thursday, January 05, 2012 4:47 PM
Okay stupid question but do all cars equipped with knock sensors have the ability to have their knock count read? Or is it just a trend in newer cars to have a more sensitive sensor than older vehicles?

As far as this exhaust debate goes, I prefer single (visible) muffler. If a car has 2 tips it better be RWD and V8 (or at least a GOOD V6) powered in my book. There are a few exceptions to said rule (350Z/G35) but no honda...even an S2000 (unless it has a V8 swap) should have dual tips.

What I really don't get is why more manufacturers can't put a center exit exhaust on cars, I mean Lamborghini and Pagani have done it and on a lot of FWD cars the exhaust runs down the center of the car halfway anyways. Another big exhaust sin to me is Toyota, if anyone has ever seen a Toyota from behind the majority of them seem to have a bend in the catback that points down and toward the center rear of the car, definitely far from straight.
Naji Dahi
Naji Dahilink
Thursday, January 05, 2012 6:06 PM
Warmmilk thanks very much for the heads up on the 2011 exhaust. Did you do a before and after dyno runs on the stock vs. the aftermarket exhausts? Did the cae feel any quicker/faster?
Thursday, January 05, 2012 6:22 PM
@warmmilk, I had a WORKS HFC on my Evo and did not have issues with melting. It looked perfectly clean all the way through with ~4 track days on it when I sold it. But I also probably ran much richer than other people which kept the EGTs down.

@JDM, any reduction in back pressure can improve spoolup and response with the end goal being to improve acceleration. Weight reduction does the same thing. There are a lot of above normal weight drivers out there in the US :) I see a lot of people spending tons of money trying to shave a few pounds here and there off their car/bike/motorcycle/etc when the easiest and cheapest place to lose it is off their gut.

@Six, I can only think of two cars of reasonable cost off the top of my head with center exhausts: Mini Cooper and Porsche Boxster/Cayman. Often times, a fuel tank or spare tire is in the way. In the case of the Mini, it uses runflats, and the Boxster/Cayman is mid-engine, so I don't think it has a fuel tank back there. Anyone know?
Thursday, January 05, 2012 6:53 PM
I was going to, did the stock baseline, and while I was installing the new exhaust the shop air compressor went out... they need that for the dyno brake or something... and the lift to get my car on the dyno. And I hadn't figured out the whole Virtual Dyno thing for my car yet.

for your 1 unmelted tracked cat there are 9 melted tracked cats...
Thursday, January 05, 2012 7:16 PM
the catback was my first mod, I didn't really feel any difference on the butt dyno...
Thursday, January 05, 2012 8:10 PM
We have run two different HFCs on the Professional Awesome Evo VII, a Magnaflow and the other a Vibrant. At times we have run very high EGTs, we have probably 20 track day/race day/practice days on them combined with no failure from either cat. The car does have a few street miles as well. I would venture a guess that I could count one hand the amount of Evo's with cats tracked harder than our car and we have had zero cat melting issues. Most recently the car made over 500whp without much issue at a relatively low boost setting on the Vibrant cat (with at least a year of hard use). I'm with spdracerut and think all track cars should require some sort of pollution control.
Mike Kojima
Mike Kojimalink
Thursday, January 05, 2012 9:19 PM
I doubt any other single exit catback is going to perform much better than the Greddy RS given the way we test it. Other results with other methods of measuring power will vary. I stand firm that this is a product worthy of our approval. I mean depending how we juggled the data to present we could have claimed that the exhaust made as much as 22 more hp.

The Greddys fit and finish were flawless and the quality of materials is also there.
Thursday, January 05, 2012 9:33 PM
don't get me wrong, I'm not saying that the Greddy is a bad exhaust or that there are much better options out there. I'm just saying its a pretty average Evo exhaust... it doesn't have any features that make it stand out from the others. there are prolly easily 10 other exhausts with very similar fit, finish, quality, and power gains. Its just that I was under the impression that the Legit stamp was for products that stand out from the pack... Judging from this its just for quality products in general. and thats not a bad thing...

any feedback on the tires? you (or whoever drives this car regularly) can pm me about it if you wanna keep this discussion about the exhaust
Matt Dennison
Matt Dennisonlink
Thursday, January 05, 2012 9:36 PM
I have just as many or more track days on my 100 cell cat. It has been on my Evo 9 since 2008 and it is used as a daily driver commuter, with work being 60 miles away from home...

The single exhaust is the way to go, plus it allows less restriction with it being a straighter path of egress...

Road Race Engineering does a Evo X stock exhaust mod. They have a how to and a explanation of the exhaust flow...

Link ----> http://roadraceengineering.com/blog/?p=1161
Thursday, January 05, 2012 11:18 PM
@ spdracerut:
The Porsche Boxter/Cayman get away with the center exhaust because, like you said, they're midship engine, and the fuel tank is located in the front, along with the spare tire.

Here is my .02 regarding the Greddy exhaust:
I totally understand where warmmilk is coming from. The Lancer EVO, being such a popular platform, it has (like he said) easily 10 different exhausts system to chose from:
HKS, APEXi, Blitz, WORKS, Fujitsubo, Kakimoto, MCR, Amuse, Tomei, Unlimited Works, Monster, Esprit, Trial, the list goes on and on. Eventually it boils down to what Chris (Marion) likes since the EVO is his car.
What I would like to see from some of these big companies is the option to run 321 SS instead of 304 (some of them offer Ti, which is great, but it's also prone to cracks, especially on shitty road like right here in California). I think 321 would be nice upgrade.
Another nice touch those companies could incorporate is v-band flanges instead of those 2-bolts with a gasket link. V-band flanges are simpler and don't leak (and don't require any gaskets).
Mike Kojima
Mike Kojimalink
Sunday, January 08, 2012 11:38 AM
V band flanges do leak. Its why you should not use them forward of an O2 sensor on a street car. 304 is not prone to cracking in an exhaust application, only in an area of higher heat like the header. It doesn't polish as well and its a lot more expensive. I only use 321 in race car exhausts with a super thin wall which isn't really suitable for long term street use anyway.

The Greddy has a larger 80mm tube size as stated in the article. Thats hwy I picked Greddy for my car as well.

Hardly any of the exhausts you mentioned have any sort of economical distribution in this country.
Sunday, January 08, 2012 6:05 PM
Sorry Mike, I'm not here to argue, but I meant that Ti is prone to cracks, not SS, if you re-read what I wrote.
As far as "economical distribution" HKS is very easy to get, and so is Fujitsubo and Blitz, and so is WORKS and Tomei too. (others being a bit harder) but I don't see the big deal. Like warmmilk said, they're all great exhausts.
Mike Kojima
Mike Kojimalink
Sunday, January 08, 2012 6:33 PM
If you select the correct alloy of Ti it won't be prone to cracking. Crappy cheap ex communist block CP might crack but 3Al-2.5V which is a ductile formable alloy of Ti with good mechanical properties won't as long as it is welded correctly.

None of those companies except WORKS and Tomei has a US presence that supports our market, they are simply carried by importers. Greddy has a engineering staff and their products are designed specifically for the US market. A lot of Greddy USA products are sourced in the USA and all parts are evaluated for function and fit by Greddy USA's tech staff here. HKS used to do this but gave it all up.

There are differences between US and JDM market cars which shows up as fit issues on our cars on some models. Guys that import exhausts cannot be of much help if you run into this. Most of the time the issues are minor but sometimes not.

I know that any Greddy USA product will work and I am confident at least in the case of this model of Greddy Exhausts, it will make more power than most on the market due to its layout, muffler design and tubing diameter. Our car is not making enough power to exploit this yet, but we will push the limit of 4B11 bolt on 91 octane power as we progress.
Tuesday, January 10, 2012 1:12 AM
these engines are 4 strokes, dont except a lot of difference in power from a freeflowing exhaust compared to another. What matters is
A/ better flow (3" is already big enough)
B/ fitment

you COULD get a better flowing system with a smaller bore if you made a lot of calculations, and end up with a quieter system. But nothing more ... once the exhaust is not restricted, you wont get much more.

If you want to see the limit of your engine, grab a set of bigger injectors, a new MAF, bigger turbo and go e85.

e85 on a turbo car has the most attractive $$$ to HP than any other bolt on, i promise. Provided you remap of course but any decent tuner can do that.

Considering knock count, knock sensors have been around for more than 30 years now. The same sensors and methods are used, and to be honest they dont work quite well. They are basically microphones with a filtering system and a recorder, which means you could not see knock, or see knock which is not there. Because when modding the engine, you can create more noise / add unfiltered noise ( think solid/ PU mounts).

There is however a promising tech coming out, based on an observation : when knock occurs, a current surge is noticed on the spark splug. I dont know if it needs a new kind of plugs, but i really look forward that one.
Mike Kojima
Mike Kojimalink
Tuesday, January 10, 2012 9:17 AM
E85 is not readily available in our area so we are not going to bother with it. We know it works well but there are perhaps only about 3-4 places that sell it in our area.

OEM knock detection is tuned to the resonance of the engine assembly combined with DSP and is a reasonably effective way to measure non audible threshold knock. Error can come in when aftermarket parts are used as this can change the acoustic signature of the engine but this can be detected by the tuner if you know what to look for. In fact I would say that it is better than any way you can do it without bespoke equipment and a lot of money and time. I am very confident that the way we tuned this engine is very safe.

Sure 3" is ok for our current power level but if we go for more power, it is going to fall short. You are not going to have more power with a smaller exhaust on a turbo engine.
Tuesday, January 10, 2012 11:09 AM
there are also plenty of american based companies to choose from: ETS, AMS, TurboXS, Ultimate Racing, Perrin, MAPerformance, Cobb, CP-E... the list goes on.

Again, I'm not saying the Greddy is in any way inferior, but it's not any better either. and 80 mm piping vs 76 really isn't gonna make much of a difference, there's more variance run to run on the dyno (especially VD) than 4 mm will make
Tuesday, January 10, 2012 11:09 AM
and some of the brands I listed above make a 3.5" exhaust
Tuesday, January 10, 2012 9:12 PM
What diameter does the Greddy taper down to at the cat? Also, is there a plan to address this issue if you change to a HFC?
Thursday, January 12, 2012 1:56 AM
+1 to the neck down at the cat end. I was seriously looking at one of these, but in the pic it looks like the usual JDM style 2.8" to meet up with the stock cat pipe.
Did you measure the ID at the cat flange by any chance?
Monday, June 18, 2012 10:58 PM
Tuning Question: So I have a stock 2011 GSR, I then install the K&N Intake referenced in an earlier article, I then have this Greddy RS exhaust installed. 1) What negative engine difference do I expect to see (i.e. knocking, issues,running rich, etc...) 2) If "Tuning" is needed to align with my mods and to get the most HP, what does this tuning mean, and who would be doing the tuning? In other words, what is the user experience? Just trying to understand. Thanks.
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