i run a leopard 4074 2200kv in a pursuit with a turnegy 180 amp esc etti cap bank for heat reduction and it runs high 40;s....its a real good inexpencive way to get some speed ....if 40mm is too small try the 5692 1090kv on 8 cell......its quit a bit more expencive that way and prob no faster u would just be able to use bigger props and bigger esc.....