unless you are a serious racer (which you could be) dont you want a cheaper back up motor like a rg or somthing? Theres a guy in my club that races with an rg and is in the a main almost every race night. But if you NEED the power go for it. Those are just pricy motors

i fergot to add that a few guys localy have tried the 21-plus 5 and have had bad luck with it. it wont idle, runs hot then cold. we checked for leaks and everything the motor is just weird. These guys are experianced too so its not a tuning problem just thought i would tell ya that. The last thing you need is a backup motor that is a pain.