I just recently put a HKS Univesal Hiper Exhaust on my car. I just changed the rear section piping and left my other piping stock. at about 3500 RPM my rear makes this rear vibration sound. I checked all heat sheild and mounts and nothing is touching. Can anybody help me??

 

My Mugen exhaust does the same thing and I can't find a thing wrong with it

 

When I had 'ziptied' my exhaust up to the hanger where the bpipe and axleback meet, it hung a bit low. When it started to hang lower and lower (before i got a rubber mount!), the Bpipe would vibrate just right to a) rub on the shiftlinkage and b) vibrate on the connection for the sway bar that comes off the lca (i have no idea what that is called). I'd check that the rubber hangers are pointing straight down and not to the side before anything else. It's an easy thing to check as a first step.

 

Happens to me to dammit, and it's fuggin annoying