i'm putting the stock h-pipe back on to get emmisions tested, but it's been sitting in the garage for a year and a half so theres some dirt and dust inside them. can i run water through them? will that hurt the cats? or should i just use compressed air?

Lmao just hook it up and start it let it run. It will burn it out. Dont waste your time 15 mins of running and it will be spotless.

not the brightest idea i've ever heard.

Hmmm. ok lets run water throught metal. Or waste time blowing air though it. Its realy your choice. I worked at a muffler shop for about a year, many years ago and our cats stayed on shelves and got "dusty" Hell we just welded umm in. You cant even tell its burning off the dust. No smell, no nothing. Thats Y i say put it on run it i mean hell its only hollow metal with plat honey cooms. Not like its a moveing part. But im not here to try to agrue i would say if you fell like you have to clean ummm use air. Metal and water dont mix.

k thanks. i just wanted to make sure they are as clean as possible so i don't have any problems with the test.