I ride desert, and up until recently have been riding solo. I thought that my 660 was fast, especially growing up on a stock blaster. But now that I go out to Ocotillo Wells with some friends from work, their yz250f's can pull me in acceleration, and catch me up top. It isn't until they run out of gear that i reel them back in. My quad isn't stock, but not overly modified either. It has +2 a-arms, axle, and +2 swingarm with long travel. Performance wise, it has a slip on big gun, and k & n with prefilter and no lid. Internally I believe it is stock, but since I bought the bike used, I can't say for sure. I am wanting to give my quad a boost in performance, but don't want to lose reliability. And since all of the mod's were done by the previous owner, I am noticing some shotty work and am questioning what the guy was thinking. When I asked if the bike was rejetted, his response was "It was dyno tuned and ran of Av-gas." I was looking at either a FMF header pipe, rev box, or just taking the thing to DRI which is only 5 minutes from where I live and having some basic internal work done. At least that way I can be confident on what is going on on the inside. Any help or wisdom would be greatly appreciated.