The next stage in our Project 135I was to add an exhaust system to improve exhaust flow and give the car a more aggressive sound. Since the BMW system is broken down into 3 parts, we decided to start with the muffler portion. In order to keep the sound clean, we retained the factory midpipes and downpipes. We do have plans to change the downpipes with the Agency Power ones at a later date.
Having proven themselves in other tuner car markets, Berk Technology has been doing R&D and showcasing their own Project 135i quite heavily on the 1Addicts.com forums. So as one of their dealers, we reached out to them on this system to use on our promotional car. With only 1 other muffler in existance, Bryan of Berk Technology fired up the welder and produced number 2 exhaust for us at Vivid Racing.
The exhaust piece bolts directly on to the stock midpipes. The piping is kept at a 3inch diameter for optimum flow. He then splits the piping from the 3 inch to twin 2.5 inch piping which eliminates the stock muffler system and exits out the rear valance with beautiful chrome 3 inch slashed and rolled edge tips.
As you can see from the pictures, the stock exhaust is quite hefty. The new Berk system takes off about 25lbs from the rear end. As we all know, any weight savings is good! The exhaust tone is PERFECTION. No drone in the cabin, allows you to hear the turbo spool much more, and when you do put your foot into the throttle, the car comes alive. Even the wife liked it so much, we made a comment on Facebook about how she was riding in the car with the windows down listening to the 135I’s sound. In combination with our Riss Racing Intake & Plenum and the JB3 Piggy Back ECU, this car made a substantial difference.
As tested on our Mustang dyno, the Berk Technology muffler system made HUGE immediate gains. Because turbocharged cars do not need back pressure, this exhaust helped the turbos start spooling much faster. At 2500rpm to 3000rpm the exhaust picked up almost 50 wheel horsepower and 90ft/lbs of torque. This is purely related to back pressure and the stock exhaust systems flap for sound causing the restriction. Once the turbos are spooled up and we hit the mid range power band of around 3500rpm to 5000rpm the exhaust holds a steady 10HP gain while adding about 10ft/lbs of torque. The peak of the RPM band at 6600rpm really did not gain any power. This is related to the downpipes and midpipes. At this point the performance would greatly free up getting the car another 20 horsepower. The peak numbers ended up being 295rwhp and 334ft/lbs of torque. Torque is what gives us the initial rush and push back and we like torque!
Vivid Racing is a distributor for Berk Technology and can supply these exhaust to any interested party. Contact [email protected] for more info. Stay up to date on our Project 135I mods, pics, and videos here at www.vividracing.com/forums/project-135i
All pictures can be seen here of the installation – https://www.vividracing.com/forums/gallery/browseimages.php?c=403
Is that thing loud or what?