P39-D is the better of the P39 line. With the 20mm you can hit easier and it does not take much to score a kill. It is really great for setting planes on fire. It has a wicked tailslide kinda what was seen in lepepe's film, and is very easily recovered for a reversal. Also this bird, you will want to come in with at least 10k in alt and work your way down. It will turn, but you have to be very careful with it.