It appears that you've got enough exhaust area under the cowl flaps. Have you run the engine yet with your cowl on? Did you reply to this thread because you are having overheating problems? If you are having overheating problems, I think a baffle will help. I mounted mine to the engine mount so I could get it behind the needle valve. If you do the same, just keep it tighter to the engines cooling fins like how the Top Flite warbirds do. I've built the TF 60 size P-47 and that baffle works well.

Also, have you balanced your plane yet? I've read that people have needed 11-13 oz of nose weight, but I didn't see any weights in your pictures.