Project E36 M3: Part 3 - Borla ExhaustProject E36 M3 (Silver): Part 3 - Uncorking the M3 with the help of a Borla Cat-Back Sport Exhaust

by Billy Johnson

We were fortunate enough to produce significant naturally aspirated power gains during the testing of our S52 vs. M50 Manifold and the Turner Motorsport Stage 2 & 3 packages for the BMW E36 M3 without breaking the bank, but the list of ways to further increase power with bolt-ons has shrunk considerably. 

The US-Spec E36 M3 is arguably the most mundane variant of the M3 and we have made a lot of progress to inch ours closer to its 321hp European counterpart.  While we gained a lot of power and some audible character by freeing up the intake of our S52 motor, the stock muffler mutes the exhaust note to a level more suitable for a 7-series than an M3. 

To free up both power and sound we installed a Borla Cat-Back Sport Exhaust (Part #14553) which was designed specifically for the S52 and the E36 M3.  Borla did not just use a standard off the shelf muffler, but rather tailored the design to suit the needs of the M3’s inline-6 to extract the most power possible with a refined sound.  We went with Borla due to their reputation for producing industry leading products and because their E36 M3 cat-back is more aggressive than stock without droning or screaming ‘look at me’, which is exactly what we are looking for in this daily driver.


Borla MufflerWith over 30 years of experience, Borla is a world-leader in the design and manufacture of stainless steel performance exhaust systems.   The Borla cat-back is one of the most popular options for the E36 M3 due to its refined, deep burbling tone and subdued, yet sporty volume. 
Bola Exhaust TipsLike all Borla exhaust components, our cat-back Sport Exhaust is made entirely from 304 stainless steel.  This prevents the muffler from deteriorating from the inside out.  Borla guarantees every muffler they make with an impressive  Million-Mile-Warranty which we think is really cool.  Borla’s exhaust technology provides an increase in horsepower and torque as well as improved gas mileage at cruising speeds. 
Borla PartsEverything is included from the mufflers, mandrel-bent tubes, flanges to the muffler, clamps, and dual round 76mm angle cut and rolled tips.  Model-specific step-by-step instructions are included as well as a few Borla stickers and a hat!  The Borla exhaust system incorporates a straight-through, less-restrictive muffler design that keeps the exhaust gas velocity high for optimum performance.

Borla has found that for street use, large diameter pipes take energy out of the exhaust by slowing down the exhaust flow and by cooling off the gasses.  Furthermore, big pipes increase the low frequency range which increases the unwanted drone.  Borla exhaust systems are designed for less restriction and keeping the velocity and frequency high to both reduce drone and improve sound quality. 

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Monday, April 14, 2014 8:24 AM
"A top tip is to always use penetrating oil on your rusty exhaust nuts. Let them soak for a few minutes and even the most stubborn, corroded nut can be removed with ease."

On behalf of the rest of the world that actually gets real rust: bwwaahahahah! :D

Just yesterday I spent two hours removing those same 4 nuts / bolts, and I'm still not done. I had to drop the entire exhaust and hack-saw the middle of the bolt to get the cat back separated from the mid-pipe, and drill out the remaining rusty bits.

Rust-rage aside, thanks for the good article and thanks as always for including the Dyno results. I'm actually surprised it was so much, even after the rest of the uncorking you've done. I've been going back and forth between the Borla and UUC RSC6. The Borla does seem like better value.
Monday, April 14, 2014 2:25 PM
"A top tip is to always use oxyacetylene on your rusty exhaust nuts. Let them turn bright red and even the most stubborn, corroded nut will probably still be slag on the floor when you are done."

Rust belt version.
Tuesday, April 15, 2014 7:26 PM
After many upgrades I've found the magic recipe to be: Headers, no less than 2-straight through resonators, one quality straight-through muffler, and as minimal diameter changes as possible. Where we live cat deletes on Hondas aren't nearly as bad for the environment as just about every diesel or smokin' (literally) V8 truck on the street.
Thursday, June 26, 2014 10:05 AM
This is awesome...I'm doing exactly the same sequence of mods to my '97 M3. I did the M50 manifold first, then the Turner stage 3+ kit, and now the Borla. So, theoretically, I should be at around the same horsepower. I plan to get it dyno'd so I'll post back here when I do.

The next "bang for the buck" mod for both of our cars, based on my research would be this: http://www.turnermotorsport.com/p-1912-samco-silicone-intake-boot-e36-m3-for-upgraded-35-inch-hfm-for-deleting-asc.aspx

It eliminates the restrictive 3" accordion ASC throttle body and replaces it with a 3.5" piece with a smooth interior. I haven't found any before/after dynos for that mod and I would love to see the gains dyno'd in another article, if you're up for it!
Monday, November 10, 2014 2:49 AM
Borla makes nice stuff, although I think the best exhaust for the E36 M3 is the one that came on it. Yes, it's heavy but it sounds good (as the video itself shows) and totally controls drone, which no aftermarket exhaust do all that well. A CAI gives some really nice sounds, uncorking both the exhaust and intake makes for a lot of noise. If you have a 95 the best upgrade is installing an OBD2 center which makes more power than the restrictive OBD1 design.
Monday, November 10, 2014 4:29 AM
We are very happy with the Borla cat-back. There is ZERO drone with this setup and combined with cams and a CAI, it is still as quiet under normal driving and freeway cruising as stock while sounding sporty and engaging when driven hard, which the stock muffler did not do. I was never a big fan of the stock muffler because it was too quiet and had no character, the Borla fixed that and was a great improvement to the driving experience of the car.
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