We have a rebuilt Perkins 4-108 and ZF-12-M transmission with the higher forward ratio of 2.63/1 in our 384. However, I believe the prop is same as original - 3 blade 16x11. It doesn't seem to get the boat to speed without maxing rpm from the Perkins. I believe the original trans was closer to 2:1, and most I have seen on this forum have the 2.1/1 version of the same ZF-12 transmission. Does anyone also have the 2.63/1 gear ratio? And did you change props to compensate? Any other recommendations to get better performance without have to get such high rpm on the perkins?