I found a way to make low handling heavy karts useful, i tried using bowser on the plane thing kart and beat the world record on bowser castle 2 by .4 seconds. Try to use any heavy fast low handking combo. And ho in bowser castle 2 and best it with drifting and try the least you can to M.T it helps me online and local (not on all tracks since online does not support some tracks send feedback on my technique!