Let me see if I can track down the guy in Nova Scotia that I sold a 20" 280 too for his V21 and see if he'll join your little internet race. I'm pretty sure a V21 will outrun a Grandsport given the same power. The grandsport is big and heavy. Its a fast party boat that looks cool. I never ran anything more then a 26P on mine with both the 225 promax and the 280 shorty that Lee now has. Boat ran into the 90s loaded up and that was 1/2" below the pad. Very conservative set up. Lots left but I didn't buy a Grandsport to break any speed records.
I dropped the nose once hitting a boat wake a little sideways. Seemed to want to pull a bit to the right but it wasn't that big a deal. I think the hydraullic steering is a huge asset. This boats a rush to drive anywhere 80+. Inspite of what you read, they are not always on the edge and ready to hook. The boat gives signs way before it would happen. Anyone can drive it to 70-75mph.
Yammer, come buy my Grandsport and put my old motor back on it since Lee's giving it away, LOL