Models that were equipped with Wright R-1820-97 nine cylinder Turbo-Supercharged engines (1,200 hp) had WEP (Such as the G model, not the E model), WEP would allow for 1,380 hp at 25,000 feet for short periods of time. Also the stress of over pressure to the manifolds often cracked pistons.
A good read through of the following book might be a good idea:
U.S Warplanes of World War II, pg. 19
Search Goolge under the books section with the exact title mentioned above.
Salute,
Ciaphas AKA Stomplab