I am going to be buying Helix up/downpipe soon and I know a guy who is taking his off his wrx and offered to sell them to me for MUCH cheaper than if i bought them new. Is there any reason not to buy these parts used? I dont know the guy very well and I wasnt sure if buying these specific parts used is a good idea.
If you can and if he still has it on his car see if you can look under the car to see if he has any clearance issue's just incase he got rear ended like me and had the exhaust pushed foward, mine is rubbing now because of it. Other wise you should be fine just get new gaskets like MY05WRX said
If he is trying to stay in the stock class that is true, but I don't understand why he wouldn't just leave the turboback and go STX. Oh well, just make sure you check them out on his car first like Ian said.