I took a demo ride on the 34 Stamas at the Miami Boat Show. It had twin Suzuki 250's mounted on an outboard bracket. It was a heavy cow to say the least and took awhile to get up on plane but once there it moved along decently.
Suzuki has test results of that boat with DF 250's on its website. I was surprised to see there really is not that much improvement in speed although milage is better with the bigger engine.
DF 250's - 4500 RPM / 32 mph / 27.2 gph / 1.17 mpg / WOT 44.2 mph
DF 300's - 4500 RPM / 32 mph / 24 gph / 1.33 mph / WOT 46 mph
http://www.suzukimarine.com/boatbuil...amas_df250.php