I have a 2 speed Traxxas Jato with the slipper clutch. as for leaving the line the slipper helps keep up the engine rpm if you have alot of traction. As for the shifting from 1 st to 2 nd it does it so fast that you can bearly hear it do it. On a real dragster they are direct drive with a multiple cinterfical clutch set up. Most electric motors will turn 30,000 rpm and with gear reduction it will make it 132 feet with no problem.