I have treid adding wieght, it does work , short shifting and trying to go from first to third, that works also, maybe not enough I have treid (that was worth 1/10 in the 1/4 ) moving the shift rpm from 6400 to 7000 in 1st and 2nd, removed the collectors, retarded the timing, smaller accelerator pump shot, a lot bigger squirter and added 50CC pumps Taller reear tires,lots of ways to slow the car down some of them unintentionally sometimes