Buick Regal GNX Exhaust Upgrade - 3-Inch Turbo Buick Exhaust Test

How Much Power Will Cotton's System Add Over A 2.5-Inch Setup?

Rick Jensen Feb 1, 2009 0 Comment(s)
0901gmhtp_01_z Buick_regal_gnx_exhaust_upgrade Old_gnx_exhaust_system 1/18

After Power Trip's scorching 10.45/128 run, there's not much more to prove with this project. Sure, a brake-booster swap from my vacuum setup would undoubtedly raise launch boost numbers from the current six-and may very well push the e.t. into single digits. But I really like the feel of the vacuum setup so I have no plans to change it now. And of course, there's the issue of a roll cage...I won't install one and cut up my ride, I've gone way too fast without one already, and this is a street car first.

However, there is one thing I'd like to upgrade: the GNX-style exhaust system. I removed the GNX suspension years ago but kept the stainless GNX exhaust on as it is a quality piece. It is a 2.5-inch system that sounds and performs fine, but there are two problems: one, the design, created to clear the GNX's panhard/stiffhard bars, runs the tailpipes fairly close to the upper control arms and the rear wheels. As this car has notched frame rails for bigger rims and tires, and I plan on getting wider meats soon-it would certainly cause interference.

And two, this turbo V-6 is flowing so much air through the 3.5-inch downpipe, the 2.5-inch system might be corking up the flow-even at pump-gas boost levels.

So in the interest of bigger rims and bigger power, I contacted Buick specialist Jack Cotton of Cotton's Performance Center and requested his 3-inch dual exhaust system. It arrived the next day, so I arranged with contributor Chris Werner to do the install at his place, and local shop TTP for before and after dyno testing. Keep reading to see how this system did.

For video of Power Trip's dyno runs, visit the 3-inch Turbo Buick Exhaust Dyno Test Video Link.

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