Hi guys, new here. Im sorry if im in the wrong place. I bought my son a used 2006 TTR 90 last year and it runs great. I want to do some mods to it for better performance. I thought I could look around on the web for some performance parts to "plug and play" and realized it may not be that simple. Can someone tell me what parts can I add and if I need additional work to have it run. Ex. I thought I could buy a new exhaust and swap out the old one. I came across a few threads mentioning "rejetting" if putting on a new pipe. (confused). I consider myself to be a youtube mechanic, if I don't know how to fix it I youtube it. As long as I have the tools and its simple enough I can fix it. Thanks in advance for anyone's comments.