P-63A had water injection too. Combat Power was 1500 hp/3000 rpm/Sea Level/60" Hg. Combat Power with water injection was 1820 hp/3000 rpm/Sea Level/75" Hg.
Performance (America's Hundred Thousand, P-63A-8, manufacturer's figures)
Rate of climb over 4500 fpm below 10,000 feet, about 3800 at 15,000 feet, 2800 fpm at 21,000 feet, 1600 fpm at 30,000 feet.
Time to climb to 20,000 feet is a little under 5 minutes.
Speed: About 420 mph at 17,000 feet, 375 mph at Sea Level.
Power Loading: 4.5 lb/hp
Wing Loading: 33 lb/ft^2