I dont see how it would add too much extra weight. Yeah i suppose the Genesis Metal gears weigh a bit more than the plastic ones, but the other drivetrain mods would be be almost unoticable in weight difference. The 17t metal gears are not that heavy compared to there 16t plastic cousins.. But anyhow, i dont race, and dont know what the race scene is like. I guess, if your a super RC nerd, every half a milligram counts, but, i think the reliability factor far out weighs what CEN gives u out of the box or in the compitition kit..

The foam tyres i have are great for corners and top speed stuff. But i have the Yokomo drift tyres on it for a reason. I like drifting.

And yeah, i have seen the CT5 kit.. Not to sure on the differences.. But i bet theres no metal gears..