Well, your 20c 5000mAh is prividing 100A as long as your motor isnt pulling more than 100A then you wont see any difference. Say your ESC is rated at 70A and motor at 60A and your lipos you have now are providing more than enough needed to run the motor to it capabilities. Now if you had a MMM 2200kv thats rated 120A as the ESC is rated 120A aswell then the higher "C" rating, lets say...30c 5000mAh would provide you more than 100A and the motor will take more than 100A and run harder. Do you know what Im sayin? There is a formula to find the amps(its like c rating divided my mAh rating, or something like that)