Hmm. I wonder why that is? I know on full-sized cars the whole point of a lighter flywheel is so less of the engine's torque is needed to accelerate the flywheel, and thus more of it is used to accelerate the vehicle. Now that I think of it it probably has something to do with clutch engagement. Maybe when you floor it, at the point the clutch engages there is less inertia transmitted to the drivetrain, and thus less off-the-line punch. However, overall acceleration should improve. Id imagine that one would have to use lighter clutch shoes or stiffer springs to get the same low-end punch as with a heavier flywheel.