I just put a 3" Invidia downpipe on my '04 with a Skunk2 cat back. All is well exept that I get a funky resonance sound coming from the downpipe / turbo area only between 3000 to 4000 rpm and only when I'm pushing it. Another way to describe the sound is something between a buzz and detonation. Nothing is loose and the heat heat shield is off comepletely (for now). All other rpm ranges seem great. Any suggestions?

 

Anybody??? Has anyone ever wrapped thier downpipe?

 

Maybe its rubbing on the hanger...mine was untill I shored it up with some washers.

 

Thanks Polyol, I'll take a look.