I have recently been looking into exhaust mods and I haven't been able to find any threads discussing the the gains in hp, and sound change that just adding a Y-pipe or test pipes would give you without changing out the whole exhaust system (mufflers and everything). If anyone could point me to a thread or answer my question I would appreciate it. Thanks in advance.

 

installed my Stillen Y-pipe yesterday...couldn't be happier.....better sound at WOT. i kept the oem muffler. The Y-pipe fit perfectly and it only took an hour to do. According to Stillen your gaining 7 rwhp with just the Y-pipe. Definitely better....more aggressive throttle response. a twin turbo 911 raced me at the light last night...guess what....i was at least one car lenght ahead in 3rd gear for about two seconds.....hehehe

 

I installed an aftermarket Y-Pipe and had the small stock resonator removed. I didn't notice any increase in power although the exhaust note did get a little raspier above 4000 rpms. No noticeable difference in sound at idle either. I guess the major gains are still to be found in a cat-back system and test pipes.

 

the 911 TT 0-60 is about 4 seconds
there cant be a way for you to even get close to being ahead unless he isnt racing (short shifting)