So I had a exhaust rattle ever since, I cut my old turbo thrush muffler off and clamped on a 08 Si one.... After putting the si one on I got a rattle noise, Maybe 5 months ago, thinking it was the muffler, I just bought a oem axle back, still a bad rattle, people said the rear heat shield took it off, rattle still there.... Really??? Took off the cat heat shield, rattle still there, then I see a exhaust hanger touching a body hanger, thought, YES found it, fix that, but still a rattle noise, WTF!! What can it be? Any ideas

 

Start the car on a lift and stand below it

 

Is your cat busted on the inside? Hit it with your fist/palm and have a listen. Do that with your whole exhaust. Let it cool off first for God's sake.

 

X's 2 .

Go to your local muffler shop (preferably someone you know)
Put it on a lift, bang on the cat ( not a hammer, you make break the honeycomb inside)
If your car rattles, it's broken, and you need a new cat.
Change all your hangers too....
Or have your piping adjusted. It can shift, if your low, or not.
It's a good idea to become a regular customer at a muffler shop ( mom & pop owned )
Chain shops tend to follow all rules...
If you are modified, just remove your cat...

I'm running 2 1/4 full Apexi ws2, headers, deleted cat..
Sounds good, engine runs good, so no exhaust burn...
But try those things first..

 

no idea..... but your doughnut gasket could be buggerd.. really need to get under it thoe (x3)

 

are you sure its your exhaust and not something else in the car? my roomates car had all kind of stupid rattles from his exhaust that were not actually the exhaust itself. if you are even semi gutted it could be anything that you didnt notice before.