Hmmmm, I don't think the guy is tryin to screw me over but I don't think he has ever done this swap on a 300zx before. I didn't have much time to talk to him because I was at work but I'll call and ask him why he thinks it will missfire with the stock system... thanks for the imputs guys, but then again I guess it wouldn't hurt to go ahead and get a new exhaust system anyway. I just want to get some info on the whole deal so incase I don't want to do a new exhaust right now. Money is tight as it is...