i have a worlds kit and i run the pro match 60c shorty lipo on blinky 17.5 (x12 17.5)i run the ballast weight,1/4oz in each rear triangle and 1/2 oz in front of the servo,i run on a med to high bite clay(west coast raceway) and the shorty seems faster,a lot better on takeoffs and landings on jumps and quicker from corner to corner,i have a full size that I've tried but keep going back to the shorty pack.i run it 2 1/2 pads in the back.i run yellow/red losi bb springs,2 pistons and 30wt and 27.5 in the rear,i also run the c hubs,the cars money right now,i am going to try the white rears and some orange fronts soon