I think I hav Leak in Y-pipe
 

About two days ago I started to hear a humming or vibration sound coming from somewhere between the passenger seats and the engine. I have a HAI and the humming sounds like its coming from there but you can only hear it when you're in drive. I know the HAI makes noise like a humming growl but this extra sound im getting is an extra hum. I had the HAI for about a month and the y-pipe and cat for 2 weeks and now im getting this sound. When you're in park you cant hear anything even if u rev up to 5k rpm. You hear it most in the beggining of 1st and 2nd gears. I also have a WSP SS ypipe and hiflow cat. I think i feel alittle loss in acceleration but it could be just me. You think it could be a leak somewhere? If so how do you check for leaks?If someone could help me out with this i would mostly appreciate it. I want to fix this problem before i install my obx cat-back.

somebody helpppp

I had a definitive buzzing from my warpspeed...i used one single layer of header wrap on the flex section and it fixed the problem for good...not sure of the nature of why...as upon inspection, the y-pipe flex section was in normal shape...not collapsed at all.

Unfortanely its not a buzz but i know what your talking about i have that same little hiss/buzz sound from the ypipe but thats fine. What i'm hearing is a hummm like a vibration of some sort. Maybe somethings lose and its causing something to vibrate and it makes a low humming sound. GRRRR this sucks. Anyone elseee??

it's normal to hear slightly louder than stock when driving at <2.5 rpm. the stock y-pipe is huge and it does control noise. on aftermarket y-pipe, it does not have any noise control so you will hear a little noise.

jack, jackstands & a helper.

Get underneath & listen for leaks, look for interference between the y-pipe & other parts of the car; also check that all bolts are tight & exhaust gaskets are in place.

yes bolts not tight is an easy fix for the noise...I just put my stock one back on today and I have the same