Rep Power: 787

20b is referring to the motor. A 20b is a 2L 3 rotor motor, as compared to a 13b which is a 1.3L 2 rotor motor.

 
Rep Power: 802

no man 20b is the chassi code hahah just kidding yeah you are right. 20b engines are really expensive and are fairly rare. Some performance rotary shops have mated rotaries together to form a 20b but only a few succedded.