Hi I have a hull thats similar a 30 ft Velocity. The boat was new in 1985 and I had it built custom with a cc, most of their hulls are encosed. the weight is also 4k net. The boat was deliverd with 2 200hp mercs model before opti max after adjustments the boat would do 60mph wot at 4000rpms the speed was 40mph with 4 people and full dive gear 12 tanks etc. at that speed the milage was better than 2mpg. all this was great but the motors were mounted hi for better performance. i blew 5 powerheads in a three year period and the warrenty was coming to an end so I upgraded to 2 300hp evinrudes,these moters were about 400pounds heavier total and the boat was a pig with the rudes. after wedges all types of props etc had to put motors all the way under,tabs full down and throw the controls forward rapidly to get up on plane. boat would finally do 70 after full throtle but at a cost the milage dropped to 1mpg at around 40mph when we were lucky most of the time it was about .9 or so. keep them for 3 years and down graded to 2 175 rudes boat would do 52 got about 1.5 mpg.kept these until recently bought a couple of used 250HPDIs having issues with these now but have already blown a powerhead anyway weight makes a significant difference the hull also has a pad and the transom is notched so their are similarities. also mercs seem to get the most out of horsepower but often have reliability issues. Doesnt suzuki claim to accept larger diameter props? Steve Stepp of velocity motors can probably shine a lot of light on your problems when I bought the Velocity he was telling me that a .250 radius on the chine would have an effect on handling etc. velocity 30