why the comparison to the bravo?
A performance boat with a 500 hp gas engine, will most likely use a bravo drive. Boats running high HP engines that require a 6 drive, are not really comparable to the slower speeds of a diesel boat.
A performance boat with a 480 yanmar will use an asd 8 correct? Will an asd-6 or 7 holdup to a 480 yanmar?
You may or may not need a drop box depending on the location of the engine and transmission being used. If you dont need one, then great, it saves a lot of room and money.