Since the 4 is a surfacing drive like a 6, I was thinking I could go about even with the bottom. ther propshaft is about 48 inches off the transom so it is just like a #6. Any input???

Not sure about the pwoer play but I would suggest talking with dan and Ken (tsunami) I know

My Fountain has a notched transom with IV's. Propshafts are 1.5" below the bottom, no boxes. I would think if your transom isnt notched, with boxes, maybe 1" below, or if it is notched, about even with the bottom? Maybe set it up even with the bottom and if needed run some spacers.

so how far back from the running surface is your propshaft??? your notch kind of acts like a box.....my boat isnt notched

I think with boxes and the right props you can do it.My 10 meter with 3"s the drives are half inch below the bottom and it runs awesome.

Your post regarding what the 4 blades did for your boat really excite me. I have only been able to run some 18x28 3 blades on mine, and cant wait to try some 4 blades that actually will bite. I can hit 77-79 with the 3 blades slipping alot, i cant wait to see what my buddys 17x28 rollas are gonna do. Planing SUCKS with the 3 blades with my drive height.

you 10M is also notched i think. how far back from the running surface is your propshaft????

It is notoched and i think the notch is 10 inches.Not sure how far back the shafts are.Mild thunder when i had the three blades they were 15.5 x 29.Best i got with them was 69 @ 5400 Rpm and that was in some ruff water and took for ever to get it.It took forever to get on planetoo.In the flat water 66mph was it I was ready to set it on fire... If I had a full boat load and full of fuel, people had to run in the cabin to get it up on plane. The boat also purpoised in the flat water.I tried to spin them in and no better.Put the four blades on 16.25 x 26 best i got 77 @ 5000rpm and gets on plane full tank of fuel loaded with people.In the dead flat water 73 Mph .Runs awesome...I did try 16.5 29 three blades and they worked pretty good but a liitle too big...Four blades are the way to go.