RE: Superstar Electric motor swap question
For comparison purposes, I believe the stock "600" motor on the Superstar EP is equivalent to a 27 turn car/truck motor. If you try to put the stock prop on the 20-turn motor, it'll have gobs more power, for a while. Sooner, rather than later, something will burn out for sure. You'll notice that flights are shorter. You'll probably discover that the motor is really hot, and probably the battery too. Then one time the motor will quit, or the heat shrink will melt off the battery...
The lower the number of turns, the hotter the motor is. That means it spins faster on a given voltage, and in turn will try to spin the prop faster. The faster you turn a prop, the more power it requires, which means the motor will draw more Amps, probably too many.
You can use the 20-turn motor, but you'll need a gearbox and a bigger prop. Look around for threads on the Superstar EP and the Kyosho Magnetic Mayhem. Those gearbox and prop recommendations will work for a 20-turn motor.