from what i've seen and heard there are many parts to an exhaust system. i dont have a whole lot of knowledge on cars, goin to go to school in the fall for that. but i need to know what does what on our evo's.

down pipe
up pipe
test pipe
mid-pipe

if there any other pipe that i need to know about please let me know. all i know is a test pipe is the replacement piping for the cat. converter. correct me if im wrong. and a down pipe is good for help in spoolin. but i need to know the purpose of each pipe.

thanks alot for the help

 

Down pipe - turbo spools faster, minimize lag
Up pipe - i think same as a downpipe, different flow direction
Test pipe - or off-road pipe, takes place of the cat-converter
Mid pipe - pipe from cat going all the way back before the rear muffler