Bought a new GYT-R insert for my 01 WR 426, but it doesnt fit right. It appears there is something else missing in the end of the exhaust. It has its spark arrestor still in place, and it did have a Vortip® which I removed to install the Yamaha insert. It appears there is a sleeve or something else that needs to be in the end of the pipe, it has about a 1/8" gap all the way around. Anyone shed some light on this? I bought it used, so I have no idea if something original is missing?