I just want to pass this along. My prop slip number was very high at 21%. I asked on EvinrudeNation.com if it was possible I had a higher gear ratio. This is the answer I got. My prop slip is 8%.
Look on the serial number tag on the motor for the complete model number. If the final letter is " B " or higher, then you have the 11:26 - 0.42 - 2.36:1 gear ratio.
Ask your dealer to refer to service bulletin dated January 2014, number 2014-01(S)