You should look at getting a 25A ESC (for brushed motors) or slightly larger. There are several out there, and the prices will vary depending on the bells and whistles you want. Just don't go to much over 25A, the larger the ESC the more weight you will add. Which ever you decide, make sure you recheck your balance before maiden. For your P51 application, I would lean towards an ESC that has either a programmable brake (turned off) or no brake at all. The brake stops the prop immediately when the throttle stick is pulled all the way back. In my opinion, using the brake feature adds wear and tear to your motor (and gear box), granted there are some applications where a brake is warranted but war birds are not one of them...