Hey guys I've got an 04 WRX sedan and it is bone stock (got to keep that warranty) and I just got Perrin Catback exhaust and when I bolted it up, first the extra bolts they sent didn't fit because I still have the stock downpipe. So I called them and they said to use the stock hardware but flip it to the other side of the flange. Thought that would solve the problem but as you've prolly guessed, it didn't. I ended up gettin nuts and bolts from the hardware store and bolting it up that way. Then the other problem came, the rattling noise! Whenever I drive the car and there is any engine break, there is a loud and vibrating noise coming from the exhaust right below the armrest area. Took a peak under and it looks like the 3" tubing is just too big and hits the under side of the car! Need help! Should I just wrap it in heat wrap? And why doesn't Perrin say anything about this in the instructionos or their website? Or did I do something wrong? Thanks for any help.