I just got done "fabricating" a stock 400ex exhaust slip on onto a 250x with a cobra head pipe. The cobra broke and it is a P.O.S. so instead of buying a exhaust I was being recourceful and used what I had. It runs and doesnt backfire. It has descent bottom end but falls off on top (I think) but I have a 400 and the 250 is my friends and dont ride it much. So my questions are is this bad? Will it be ok? And what should the jetting be around, I have no idea where to start?