There is a pretty good article published by Hot Rod magazine, where they tested various combinations of electric and mechanical water pumps, and underdrive pulleys as well. All changes have been backed by dyno testing.
http://www.hotrod.com/articles/hrdp-1201-baseline-testing-do-water-pumps-suck-power/
CN: The better electrip water pump (Mezeire) made a 4 BHP difference on a 530 BHP 372 CID SBC over mechanical water pump. Next time anyone tells you they are good for 10 to 15 hp on your stock 5.0 HO, you should think twice about their credentials.
http://www.hotrod.com/articles/hrdp-1201-baseline-testing-do-water-pumps-suck-power/
CN: The better electrip water pump (Mezeire) made a 4 BHP difference on a 530 BHP 372 CID SBC over mechanical water pump. Next time anyone tells you they are good for 10 to 15 hp on your stock 5.0 HO, you should think twice about their credentials.