Hey Flytyer, I also have 21 ft trophy, I repowered it april 2007, it had the factory 120 force anchor! Anyway I put a 1997 merc 175 hp 2stroke on it, it has lots of power and I've had no trouble with it, it's sweet spot is 30mph at 4200 rpm,only problem with it is I burn 60 ltrs an hour ouch! So if I had the money I would go with a 200 hp Yamaha 4 stroke, because the trophy is such a heavy boat, I believe my manual say's 2800 lbs add 82 gallons of fuel which is what around 800 lbs plus gear and buddies it adds up real quick. Hope this helps.
Cheers