Check in your manual to find out the Kv and maximum wattage of the motor and look for the equivalent. An increase in Kv means an increase in speed with any given battery, but also increases your watts if you don't go to a smaller prop. That might make you burn up another motor if you go over, but will definitely reduce your flight time. It might be in your best interest too to figure out why you keep burning up motors before buying anything else. Are you going over the max wattage? Inadequate cooling maybe? Too big a prop will do that if you've changed from the stock one.