I will tell ya to listen to the power mongers that are speaking here!!!! My 18' sled came with a 115/80 hung on the back and we had to run it on the ragged edge to get on and maintain plane. Well needless to say we learned the hard way and that motor lasted about 100 hrs. Have the 150/105 on the back now, all I can say is what a difference!!! 5500 RPM is the normal top end of most motors and with the old one we consistantly ran at 4800 and above, with the new one once we are on plane 4000-4200 is the norm. The boat will carry more friends a lot easier also. If the sled will take it hang the 150 on the back, you will not be dissapointed.
Good luck and tight lines, Jeff