Always heard if you go past 70 mph you had better have external steering for safety sake. Sounds like you have already pent a significant amount of $$$$$ on the boat and motor and I would better that sooner or later the torque placed on the drive at those high speeds will get the better of you. Besides that it just really looks great hanging back there with the drive. Good luck, I think I have heard around 3500-5000 for a good dual ram system. Lantham marine is the best!!!!!