[magman]

I would put the money into the diffs., then trans to make them bombproof. Good bulks are a good idea as well as kids will hit more stationary objects than an adult would. The combo bulks/diff set up Mike sells is very nice and it uses 1/8 gears to really make it sweet! Also in the RCM store are alternatives if that is too expensive. Arms and driveshafts are easy enough to change so rpm arms would be good. On say a 4s set up a mmm/Tekin esc would be good.

The problem w/limiting speed is that the esc's run cooler/best at higher voltages and speed when geared correctly. ( more efficient ) So for a motor say a 2000kv truggy motor on 4s will be a good starting point....not crazy fast but fast enough to keep them entertained. They, kids, will have to learn throttle control.