Had new 540 dyno'd on Superflow and got 600 HP at 5,000 and 686 ft-lbs at 4,200. Numbers were what I expected when running dyno headers and no water pump, alternator, or power steering pump. What would be expected drop when adding in these items along with Stainless Marine exhaust? What would you expect the "corrected" numbers to be adding in all these items?

See if you can get hold of Axa Powell on here, he might be able to guide you. If I remember right he was north of 700 with the dyno headers but dropped to a something over 600 after the accy's and wet CMI's were added into the mix.

generally you loose app 100 hp at the prop due to parasitic loss,this includes drive unit loss[bravo].

About 10hp per accessory and 20-40hp for the exhaust. The loss for the exhaust will depend on what you have in comparison. A Bravo drive uses about 30hp.