Thanks Jason.... Pardon me for being kind of new to this repair, are these nuts going to be found in the engine compartment side of the transom?

Outside & above the drive. They are 9/16 socket size. You'll find them at the very top of the transom housing at it's most thin point nearest the top. They will be directly below the rectangular "mercruiser" decal.
They are nuts that hold a "U" bolt to the steering pin. Torque them "Oilfield tight". That's really, really tight with a 3/8 drive ratchet.

Full hydraulic steering is needed.

Definately a steering issue. I'd also recomend getting hydraulic steering running that kind of HP. Good luck with it and I hope you have as much fun as I've had with my 240 sport.

ok i have 718hp full hyr steering i put a bravo one prop on my boat and that made my boat handle good. i now run in the upper 80. http://www.youtube.com/watch?v=jmnD9...feature=relmfu i was running a mirage prop doing 80 in this video you can see i chine walk a little but now i don t with the bravo one good luck