I have a 2005 20' G3 pontoon with same year 60hp yamaha 2 stroke. Transom rated for 100hp. I just don't have enough power to give my grandkids a good ride on the tube. Would moving up to 90hp Yamaha be worth it? Both the 60 and 90 are 3 cylinder motors. I don't need much .... maybe 5mph would do it. With the 60 I can get up to 18mph with 4 people no tubers. Any input would be helpful ..... thanks!