Gear drives are hands down the way to go for racing. I don't know anyone that races a procharged combo with a belt drive that doesn't get tired of constantly dealing with belts. The other advantages are - easier to change drive ratios, less drag than turning a large belt, puts the weight low and forward (at least for radial racing), and the blower inlet is front facing usually without any obstructions so good, clean and cool air. Two disadvantages - initial cost and packaging. You'll need to get creative with radiator location.