I've got a new 05 WR450... this thing is stock as stock can be. I haven't done one thing to it. I have been reading about jetting, and can't decide if I should do any custom jetting, or leave it stock. After the free mods, does jetting really make that much more difference? Or can I get a big improvement just from the free mods? Also, is jetting easily done? I'm no expert, and I might not even know if my bike is "dialed in". I'm just afraid to mess with anything that I don't know about.