My Dad and I worked hard on all the mods for my 4-wheeler,

Hetrick race pipe, high performance clutch mod with a delta rear clutch and 5.4 rollers on front variator.  Battery box removed, oil injection removed, premixed at 32.1 with maxima castrol 927 racing oil.  Works shocks all the way around, ITP holeshot front tires mounted on 10 inch 3x2 offset blue Douglas rims, Snow Hog rear tires mounted on 8 inch 2x4 offset blue douglas rims. Pro design kill switch.
 Mikuni 24mm carburator, sea level 800ft, running a 140 main jet, needle clip on 4th postion, air screw 2 turns out, uni air filter with outerwears and , new intake manifold and malossi reed cage, 27 tooth rebel gear rear sprocket with a D.I.D chain and tensionor, +3 a-arms,+2 Hetrick swingarm and wheel spacers on back.  Reinforced frame with gussets,Douglas v-series bumper, Tag handlebars, ac nerfs with heel guards, billet starter block off plate. WRH high compression head on the way.

. p.s. My Dad helped me with this list a little!