My WR426F 2001 (purchased in Brazil) is a European Model, that comes with a stainless welded muffler. Different from the US bikes, the pipe/insert cannot be removed by just wrenching, even when opened, I even don't know if it has an easily removable insert. It requires sawing, and welding (stainless steel). Can anyone tell me if it worth sawing this pipe open, and if so what has to be done (in terms of modifications) to unleash the power of my WR426? Once uncorked, what about the pipe, (between cylinder and muffler) this is not a 2 stroke bike, is it really worth changing this pipe? What does the bike really gain?