Most of my motorcycle background is riding Ducati's around race-tracks. I have recently discovered trail riding and absolutely love it (the poor DUC is gathering dust)! I recently traded my XR400R on a barely used 2003 WR450. When the previous owner mailed the manual to me yesterday, I noticed the model number is WR450FR . Is this "R" common to all US models, or does the "R" imply differences from the 450F (local Honda dealer doesn't know)? The reason I ask is because I would like to do several of the performance mods (I have the larger pipe opening, and plan to do airbox, grey-wire, and jetting mod's..."04 starter upgrade also), but do not know if the difference (if any) will affect my approach. Thanks for lending advice to a new WR fan!