So recently I installed megan racing test pipes onto my 07 g35 along with that came the horrible rattle noise that sounds like metal hitting metal but it’s obviously not that and it commonly know as rasp/hiss i know I have no leaks or lose bolts I checked it all. It coming from inside the y-pipe and the flex pipe. My guess for this noise is the test pipe diameter is 2.5” and the y pipe diameter is 2” so it’s trying to force lots of air into a tiny pipe and messing up the air flow and this causes the rattle/hiss noise. I also have a single exit y-back exhausts. I’m hoping that replacing the stock y-pipe for an after market one would get rid of this noise but just wondering if anyone has fixed the issue by replacing the y-pipe and what brand. I can also try and get a video uploaded of the noise. Any input is helpful thanks guys.

 

My guess is the flex sections of the Y-pipe are torn.

ISR makes one of larger diameter that doesn't have flex pieces.

 

yeah I was sorta thinking the same thing I’ll have to check out the isr y pipe hope that fixes it

 

Stuff like that can be repaired by a local reputable muffler shop, those flex sections needing to be cut out and replaced is fairly common. Whole lot cheaper than a new Y-pipe.