I'm gonna be changing my y-pipe with this http://www.ebay.com/itm/MEGAN-RACING...097#vi-content I was wondering since it's 2.5" at the inlets while its 3" at the other side. Isn't the stock midpipe inlet 2.5? will it line up with the holes? Reason i'm changing it is because the pipe is making a rattle when it's cold. Especially when i accelerate. Car is a '07 Sedan RWD.

 

Decided to update this thread with my findings. It wasn't the y-pipe that was making the noise. It's the mufflers. There's a TSB for the G37 where the muffler's baffles break inside causing a noise that sounds like a tin can getting sawed when accelerating when the engine is cold. The car sounds like sex with the mufflers off No rasp whatsoever. Doesn't sound like a civic at all lol. It's just only much louder with that same VQ sound. No drone while crusing as well.

 

I have the same noise coming underneath from my car. It's so fawkkin annoying, I don't know what it is. I'm going to start with changing out the Y-pipe, anyone know the outlet of stock cats and inlet of stock mid?

 

Before you throw money down, i suggest you remove the mufflers first and see if the noise goes away.

 

I can't decide if I should go aftermarket or stock. Does it make a sound difference if I go aftermarket?

 

Differences in sound will depend on what brand you choose. Look up videos in youtube on brands like tanabe, Invidia, megan racing, Strafe, and so on. I myself am going with the invidia q300 setup due to it being a relatively quiet exhaust. A little rumble then a loud roar when you WOT.

 

True, just annoying on choosing which setup to go with