I've found that most Spit IX pilots will use the same tactic - turn as hard as they can with the throttle wide open. In this situation, the G2 will gain an advantage if it uses WEP to climb above the Spit IX's loop and stay topside. Since the Spit pilot is yanking so hard, he's bleeding his energy and will have trouble bringing his nose up for the next merge. Of course, if you've misjudged his speed, he'll be in a position for a tail shot on the G2.
A lot of pilots instantly think the G2 is the G10 and expect it to zoom away. By going with a nose-hi yoyo turn, I've gotten inside the turn radius when the Spit pilot had gotten complacent and wasn't expecting me to be high and behind him. The difficult part is that the prop torque will twist the nose around so its hard to line up a shot.
A G2 will own a P-51 in a high-speed turnfight, no problem. Same with Corsairs. I would've had a couple of them last night but I got combo'd by Stangs/N1ks and then Corsairs/LA-7s. P-38s can be a little trickier if the Lightning pilot knows his business, or if the P-38 is being used for jabo work.
I learned a hard lesson that the G2 should not be used as a bomber buster against B-17s.