What makes Nail'd so crazy is the speed you'll be going when you have boost. Press A and you'll get a short burst of nitro and if you want to refill it you need to land jumps properly (and perpendicular to the ground), do feats, or simply go through the flaming gates and hoops. Word of wisdom: don't lay on the boost for a long amount of time unless you need to get somewhere very quickly, I found doing small bursts (even simple presses of boost) was much more efficient as I didn't seem to go faster when laying on the nitro (though impossible to tell since there's no speedometer in Nail'd). http://naildbiter.com/sL8ya