bigest badest motor on 5s lipo

[stampy]

im getting to the point were i need to start to think about somthing to power my custom monster im making, i dont have a clue how much it weighs so my guess is 12lb+ when i get it rtr. so whats the best motor to power a big heavy monster truck on a 5 cell lipo pack? i wont speeds that will top near 50 when geared right but i also wont tree stump rippen torque when geared low :D