I have SLP Tri's with its funky **** y-pipe going to a 3in pipe where my CAT used to be but from there it runs thru the factory IROC exhaust piping going to a Flowmaster muffler.

Would I really notice a difference or pick up any HP/TQ if I was to go with a 3in CATBACK? I think the IROC piping is 2-3/4 til you get to the rear axle then it takes all kinds of bends and crimps and crap so Im sure the diameter is smaller in that area.

whatcha think? any proven results?

 

I think you should notice a reasonable difference. After all most people just install the catbacks, youve already done all the work in front of it and I would think that the catback would help it out.

 

The catback will help out more than you think. All of those tiny kinks and bends in your stock exhaust inhibit flow. Since you have the majority of the restriction elimintated with those headers your gains will small but important. You may not feel it as much but a dyno graph would really open your eyes. Especialy since you have a cammed car.

 

Get a cutout after the slp y pipe and you'll be set.