If you guys are looking for some more speed why dont you just find your self a local engine builder thats good and let him go to work on that SB the perf parts are cheap cause there everywhere and ill tell you i have built some STOUT SB,s up to 700hp 400 ft lbs of tourque with a good port & polishing on stock cast iron vrtec heads a zillion cams that will put the power at the rpm.s you want it in my sleep i could get 400 hp for a 3rd of what that 8.1 will cost you no gas tank issues then fit your 3 outdirve and youll still have money left to stock the bar in the boat and invest in a nice thru hull exaust so you hear the cam bump and you breath well kinda like having a boat sleeper