They may be a little louder than what you're looking for, but I put a 3" TTI X-pipe and Dynomax UltraFlo mufflers on my race car and it picked up a little bit! I figure the X-pipe helped and the mufflers didn't hurt. I also get compliments on the sound at the race track. The "X, or an "H", may also help tone the sound down a bit.
