recently i installed an ams 3" downpipe, and the ams 3" testpipe onto my ams 3" catback onto my Evo 9. ever since we installed it i get a wierd metal and metal sound, almost like a klunk whenever i start in first gear or when i come to a complete stop (pretty much whenever the weight of the car shifts). i got underneath the car again and all bolts were tight and the exhaust seemed solid. i also have recently gotten an OEM clutch installed by mitsubishi on my car as well, since i burned through the first. any ideas to whats causing the sound?

 

There is a metal fram (a heat shield) that follows the exhaust, it is bolted to the car not the exhaust. Anyway it starts about where the stock cat would be and goes back. It is flimsy as hell and could be it. Other than that remove your crossbars and see if that removed the problem, then you need to space them to reinstall. It might also be the pipes hitting the frame or various engine components. The exhaust system moves alot forward and back.

I would suggest you look at the heat shield. Especially the section that sits over the flange for the cat/DP connection.

 

check the gap beetween the downpipe, crossbar, ACD, subframe, & oilpan. those are the common spot where the downpipe could hit, especially when the are 3" in diameter.