I have a 260 hp volvo 280 drive. I dont know why but I hate it performance wise. It is the oem motor/drive that came with the boat.(freshwater) Runs great never had any issues with it so I dont know why I hate it, just do. They are suppose to be really good drives though.
When I repower I will be going with an mpi enigine drive package. (I need to do the transom anyway)
I dont pay too much attention to the numbers but I know I run 30-33 mph on cruise and can top out about 37-38. A buddy just bought a slickcraft (ugh) with a 210 hp mercruiser with an alpha drive and he can smoke me...... till it gets rough.