I put my down pipe on and IT rattles like crazy when I rev. I looked under were it could hit and it really close to the diff. its a evo 8 no ACD what can I do without buying a new down pipe.

 

See if the cross member bar is touching and smash it with a hammer OR find out if a bolt is loose.

 

its not the cross member I looked again and its hitting the diff. can I put something in between it

 

Damn that suxs, What type of downpipe is it???

 

if u dont want to buy a new downpipe. then just take it to a muffler shop and tell them to heat it with a torch (where it hits) and smashed lightly for it doesnt keeps hitting on the diff. thats what i would do

 

Stainless Steel is much harder than alluminium, and in time it will wear your diff housing....how bad?? time will tell.

Couple of options -

1- Take it to a pro-exhaust joint for some hammering
2- DIY with a ball-peen hammer after marking where it touches (a little at a time)
3- Put some heavy duty thermal wrap between the pipe and the diff housing at the point where it touches. (this will not last so its not a long term solution.

Ive seen and fixed a few of these, especialy on the 3 inch DP. A minor dent to clear the diff wont harm performance (though it will make the pipe look worse for wear if you ever want to sell it), however it needs to be sorted.

One of the main culprits is the engine mouniting in the front & rear which are very soft, and allows the engine to rock, thereby making the noize worse.

PS. As I work with S/teel all the time....Stainelss Steel and flame torches dont really go together very well! Rather press it or hammer it.