madrat.what motor should i use

[nigel63]

i bought a madrat to try 10th buggies for fun,it came with a 21t brushed motor and 3800nimh battery,its very slow and would be no good watsoever to race,it needs brushless and lipo i knoe,but what turn motor should i get to be on pace,8.5t? or lower.a hobbywing combo is reasonably priced,any thoughts and ideas to get it to go please.