Re: Would the lack of an exhaust bellows...
The anti-ventilation plate on your outdrive should be on the surface of the water when your boat is on plane. Look at where the exhaust tube is in relation to the anti-ventilation plate. It's above it. If you've ever had an exhust bellow or tube come loose while on plane you'll hear the immediate ROAR because it's now exhausting into the air, not into the water through the prop.
It could possibly have some minute detrimental affect when trying to get on plane, maybe a couple of thousandths of a second or so. On the other hand, it might actually help you to get on plane, kind of like vent holes in your prop ....
