overheating issues?

ok well i decided to get the MM and a feigao xl7 and go 4s. I figured that i would save more money using a 4s and getting more RPM using the 7xl, even with a 16 tooth pinion i get 42mph, and with a 18 pinion i can get up to 49mph which is insane. by using all of these i can avoid overheating alot and the esc will handle it easily.but either way i am wither making or buying a heat sink for both the motor and the ESC. WHat do you guys think? the last thing i need is a cheap good charger, im thinking of the venom charger, by buying both the ESC and the charger there i can save $30 which sound like a good deal to me.