it does sound a little OP... how about adding it right here:
and if someone attacks you on the back while spining you can die or get thrown on the ground like when spidertron's bomb hits you.
so thats why you add speed on the other upgrades, or maybe that will make it bad...
or make it stop at own will so that you dont get hit when a jetpack robot is rushing at you
i dont know, i might make a little animation to demostrate my idea.