Hmm tough question, Orion V2,Epic Shock,Reedy World's Mod very low turn brushed modified motors with proper gearing will be very fast,over 50mph fast.And this with a normal cell count,this is blazing fast.Just a little slower than 1/10th nitro racers.
The best out of those I tried,Team Orion V2 series mods,second the Epic Shock.