Guys it's not drag racing, your fmf pipe is just fine for xc, fmf verses a toomy isn't going to determine if you win a xc race. I would go race like your blaster is right now and just have fun until you get cash for better parts, my first xc race was on a kawasaki mojave 250 and the only things aftermarket were a k&n, dg pipe, and razr rear tires; heck it would've been bone stock and I stil would've raced it and had just as much fun. It still doesn't have much more done to it and I've beat plenty of 450's in the woods.
Tires: Go with maxxis razr's and a 20" rear tire for a 9" rim, 8" has too much sidewall(2's only for front, the rear doesn't matter if it's razr 1 or 2, razr 1's will be better for a small bore machine) itp has too soft of a compound and they wear too fast
Width: You will probly want 46" or 47" on the front and 45" or 46" on the rear.(wider in the front gives you much better cornering ability) The minimum width for most xc tracks is supposed to be 49" but I threw on some extended hubs to 48 1/2" for my last race and found out you will hit some trees.
Rims: Standard aluminum rims are fine for what your doing but DO NOT get anything less than a .190 aluminum rim if you're going to buy aftermarktet rims, I've already destroyed two .190's in the last season and a stock steel rim so a .160 or .125 will get trashed quickly.
That's all I can think of for now...
