IMO, 17.5 is sketchy for MM. Not because MM sucks or anything weird. Its power and heat. The car is heavier unless you spend $$$$$ to make it light, and in general 17.5 motors are run hot to get speed out of them. But the MM has much less cooling, so that makes the whole thing worse. Almost every mod car at the local track is MM and they can do wheelies all day with the traction level. But in stock, 90% of the cars are RM. Mostly for the power. MM handles just fine. I am hoping to put together a mod MM car soonish. I need a second class to run.