i run the novak 4.5 550 in mine and its perfect, 550's are more torque than full on speed so with the weight of the losi it is still controllable enough, i run either a 12 or 14 pinion depending on track and its still accelerating at around 40m straight, make sure you go for a good speedo though, i use a lrp sxx v2 tc spec and it is very well matched, tried an 1/8th scale esc and it was not enough for the big motor and needed a reciever pack to run the steering,
i love my losi even though those bloooming durangos seem quicker its not by much!!! but got the BCE lightened chassis on the way and will be getting the TLR tuning kit!
have a laugh with it i doubt youll break it