In my experience the drivetrain is more of a limiting factor than weight with the fgx platform. The internal ratio is 2.71:1 where the solid axle is obviously 1:1. people are converting their fgx chassis to belt which helps but the new internal gear ratio isn't that much better at 2.5:1. Most are very limited with gearing choice as well. I know from first hand experience that a slimmed down independent suspension chassis can be just as fast if not faster than a solid axle car at a smooth large track like Tamiya
