i own a stock 93 rx-7 and my wife got me a power fc. She got it for me as a gift but i didn't tell her that I was planning to go 20b. I know that the 13b is capable of monstrous power but the torque is a bit lacking. I know that the fc is tuned for 2 rotors out of the box but is there a way to upgrade it to a 3 rotor capable stand alone?

 

NO, you have to sell it now.

 

Do a little research on the forum for 20B. It's not just that cut-and-dry. Get the PFC tuned and keep the 13B IMHO.