I have an '02 YZ250f and wondering if all the parts on the WR is interchangeable with the YZ? What exact years of the YZ/WR are compatible? I need to get a spark arrestor, but want to get something that wont break the bank. I was looking at a promoto end cap for my stock exhaust. How are those installed? Do they just slide over and clamp on? Well, I was thinking of switching to a '02 and below WR exhaust because they have spark arrestors and I can get them cheap. I know they have a baffle in them and therefore decrease flow and performance, but I don't mind. I am just a beginner and don't need all the power from it plus my stock exhaust has a huge ding underneath.