I’ll throw in my .02. I started last year in a shifter. I wish I had started in TAG or Rotax. I primarily run on the big courses but I run at MMX (GoPro Motorplex) in N.C. too. At the sprint track, the TAG/Rotax karts are every bit as fast as the shifters. Both types of karts post almost identical lap times there. The difference is LOTS of guys are fast in the TAG/Rotax karts where there are only a few guys in the shifters who can run with them (I can’t). On the road course, the shifters post better lap times. The single speed TAGs have to compromise acceleration for top speed and vice versa on the road courses. Even so, the TAGs are still fast (WAY faster than rental karts). If I could do it all over again, I would start with a Leopard. I know some guys who left shifters for the stock Leopard class because the racing is better (more guys can drive them fast enough to be competitive). There is a two speed Rotax motor called a DD2. It’s cool because it is direct drive (no chain) and has paddle shifters. I rarely come across one of those though. Good luck. You are going to have a blast no matter which one you choose.