First off, Kurtis@MBSP sponsored this test. He is deserving of the credit here. I am merely reporting because i am a superstar.
We went to Charm City Tuning this afternoon, super hot and humid. They've got a dynojet in house there. Strapped it down.
7lb flywheel and light crank pulley
home ported head, and competition valve job
2.9 clone upper intake
Ported exhaust manfolds
2. 5" TT with Borla with 42dd testpipe
The best pull was 197whp
Next, we backed the car off the dyno, and Kurtis threw on the 3" setup that is available in the classifieds. Kurtis@MBSP
The best pull with this exhaust was 204whp. This gain was the whole powerband, and 7whp at peak. It also helped churn a couple lbs of torque across the entire powerband, and 5ft/lbs at peak.
I now run a 3" aluminum, single muffler system made by Kurtis
-A mildly modified VR will see mild gains from a 2.5" to 3" exhaust. If you're planning on modding the motor to anything more than bone stock, it might make sense to just buy the 3" system off the bat.
-You 2.25" lovers are wrong. I just pooped on your 'low end torque'.
-Don't be scared.