Based on what I have read, the P-39 could turn a full 360 degrees by the time a zero turned 180 degrees due to the nimbleness of the P-39 since it had its engine near the CG. The two main reasons the US didn't use them as fighters (Based on what I have read..not saying these are the only reasons

)
1. No Supercharger (As mentioned), therefore they didn't have alt capability to escort the Bombers.
2. The Terrible spin characteristics due to the Engine being located near the CG. I remember reading (Not sure where) about Soviet P-39 Aces, and they said the main thing the pilots had to beware of was stalling at the top of a loop and entering an inverted flat spin.
However, it seems the more I read about the P-39, the more it just recieved a bad rap. Granted, I can also understand that it was probably a handful to fly if you didn't pay attention (e.g. that flat spin) and the USAAF wanted planes that had more benign stall characteristics.
Can we add the J7W1 or McDonnell XP-67 just because they look cool?

I'll settle for a Tigercat though!