i posted this in evo general but feels this is the right place for it.

I have been driving the evo around town cautiously. downshifted to 2nd gear as i was slowing down at a turn when i hear a really loud rattle near the bottom firewall.it sounded like i was dragging a pipe!! i immediately pulled over and checked the under side but there was nothing out of place. I even tried to shake the downpipe and it felt solid.

Only thing i could suspect that might cause to do this is the joint between the dp and o2 housing i bought the DP from a fellow member . the upper opening to be 2.5" and the lower to be 3". I could not use the stock o2 gasket nor a standard 3" gasket because it would hit the donut gasket seat. so....I used the steel 2.5" gasket from the old catalytic converter that i had laying around. would you guys say that this is the cause of the rattle?

also, what do you guys consider a great dp?

thanks!

 

all you need in there is the doughnut gasket

 

that is one of my problems. it would not seat a donut gasket. see pics for reference:

 

got this fixed. the dp was hitting the acd. i got another dp that has better clearance than what i was using...