Hi guys, as I’m sure some of you know ive got a (basically) stock ’01 400ex . I’ve been starting to ride some track and have found myself wanting a tad more power. I want to keep it relatively stock for resale purposes (no big bore) my question is, what kind of power increase could i get from an aftermarket pipe? Slip on, or full aftermarket? Will this on its own give good power or will it need a rejet? And again, what kind of power will it produce over stock? Any anecdotal advice or opinions from some of you more experienced folks would appreciated. Cheers!