I've just fitted a Delkevic system to my 2017 650XT. The downpipes (headers) stay in place, and I'd assume any company who make an aftermarket system would use the standard downpipes, as they can't really be improved, and are already stainless.The front downpipe would be easy to change, the rear less so as its up behind the shock- joint at the downpipe joint is easy enough to get at though. I would imagine a standard system would just bolt on to what you have. My standard system would be available if it's what you need, I don't think I'd go back from the Delkevic