Project Gen 3STi: Testing the COBB Down Pipe and Exhaust Project STi AccessPORT COBB Tuning AMS automotosport rallysportdirect proto down pipe GR cat-back exhaust MotoIQ Certified Legit
Here is the AMS Stage 2 Pro-Tune versus the Cobb off the shelf Stage 2 MAP. With AVCS tuning Mitch was able to make slightly more power under the curve. This makes for very fun street car. 


Project Gen 3STi: Testing the COBB Down Pipe and Exhaust Project STi AccessPORT COBB Tuning AMS automotosport rallysportdirect proto down pipe GR cat-back exhaust MotoIQ Certified Legit
Our stock baseline compared to current dyno. Never mind the before and after #'s. Let's look at 3700 RPM's. Peak gains of approximately 130LB FT of torque and 85 HP. Turbo cars are FUN!

After living with the car for a few weeks at this power level it is quite fun to drive and has very usable power. The turbo comes on instantly yet it still pulls to redline. I DO notice that the STi likes to be short shifted or it seems that you fall past torque peak. We also have been using our trusty AccessPORT to data log and monitor things to make sure the AMS MAP is perfect. In logging with the AP one thing that we learned is that the stock wideband does not read below 11.0:1. After confirming this we have been monitoring Fine Knock learn and the car logs ZERO counts. We also noticed and confirmed with Mitch that when monitoring individual cylinder knock, cylinder 4 is the loudest and will log very high knock counts which is actually feedback. One theory is that this is turbulence in the intake manifold... So I guess we found the next things to address in making more power... Regardless of what comes next in power production the Cobb turbo back system is truly first rate kit. Are there cheaper alternatives? Yes... Do they perform as well... Some might... Will they last as long... EHH I wouldn't risk my money on that. With the extreme attention to every detail we deem this offering to be MotoIQ Certified Legit.

With the car's newfound power we are starting to notice the limit of the OEM suspension setup and quite honestly the steering feel is very vague, especially on center. We will be resolving these things and more as we continue to tweak Project STi...







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Thursday, May 24, 2012 12:13 AM
I love how that downpipe is comparable with any kind of exhaust. But if you have Cobb up front I'd go Cobb all the way...
Thursday, May 24, 2012 12:14 AM
Thursday, May 24, 2012 5:30 AM
The muffler sure is shiney.... you can see Wes taking the picture in it! I can't believe how crappy the stock downpipe design is. I wonder if it's the same deal as the Evo X downpipe where they have a nasty inlet section due to having to be compatible with RHD.
Wes Dumalski
Wes Dumalskilink
Thursday, May 24, 2012 6:31 AM
I laughed out loud when I removed the OEM downpipe Khiem. Holy new level of OEM suck! I DO like the use of the OEM donut gasket and bolts at the down pipe to exhaust junction. Honestly the car is pretty darn quick as it stands. Time to plan the power mods. but get BUSY with bushings and suspension.
Saturday, May 26, 2012 9:47 AM
You probably already know, even though the Cobb system necks down to the 2.5" OEM size at the donut gasket, you can still make great power.

Another bonus about Cobb parts, at least for the Subaru community, they seem to hold their resale value really well and are bought quickly on the forums. I think that says a lot about the quality level that Cobb puts into them. Makes them desirable even used.

HKS used to make a Subaru down pipe for the GD. It was 3" non-catted, but it had the stock flat flange at the turbo. I guess it would be good for an external waste gate setup.
Wes Dumalski
Wes Dumalskilink
Saturday, May 26, 2012 10:17 AM
Ya know I am kinda surprised someone hasn't modded the stock down pipe to separate the wastegate flow...
Dan DeRosia
Dan DeRosialink
Saturday, May 26, 2012 3:21 PM
Hmm. I have a TIG welder... maybe when I got stage 2 I could try for grins. Although the stock bits are just mild steel or something, no?
King Hax
King Haxlink
Thursday, March 14, 2013 1:37 AM
The Bends are more gradual and it helps to prevent boost creep but also allows the COBB downpipe.abwe
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