I don't knoww too much info om the HPI MT, but if the chasis and drive shaft set up is the same as the MT2 the .18cv-rx is a drop in fit all you need are motors mounts and a washer (part z699). I supose the .18 tz will fit too, but you need to upgrade to heavy duty gear shaft setup, and I have not seen a mt or mt2 with the tz motor in it yet, but I know I will soon. I just put the .18 cvrx in my MT2, it's a pretty sweet engine plus at $109 its a good deal. goodluck