About 20 hp less at the propshaft and 40% less at the gas pump. To quote another "According to Rick @ merc racing changes included pistons, reeds, compressor,computer, injectors, ect. Thought Rayzor mentioned new block #'s as well. Fuel cooler loop is eliminated, fuel hose routing changes, t-stats dump through the bottom pan, compressor dump line is poked out the back of the lower cowling. Can't speak to hp numbers but was told 240 give or take. Engine ID states 225." They also have raised rev limiter, 15" mids and 1.75 Sportmaster cases.
I just had a stainless steel 3.0 liter driveshaft installed in mine as they still suffer from the corrosion at the wp seal.