you need to remember that top speed and take off power is not just engine alone. you need to consider the power to weight ratio. the final drive train ratio. tire size, etc. I used race my mammoth against savages they would beat me off the line but my 2nd gear final drive ratio was so high that in a long straight i could pass them with ease. If you are just running short distances gear your truck low for greater power off the line. and the gear it high if you are doing long straights. If your racing him at a dirt track find a gearing combo that gives you plenty of grunt coming out of the corners but lets you run the straight with out running out of rpms. also do what you can to lighten up your truck as much as possible without sacrificing durability.