I feel your pain,I fish 95% of my time at 5700 to 6000 feet above sea level,Im Running a 2015 Cougar powered by a 250 G2 , started with a 26 Raker 2 then a 25 Raker 2 and now imported a 24 Fury.Best i can get is with the 25 Raker 5650 rpm and 74mph24 Fury gave me 5750 but only got 73mph.Verado kicks my butt every time, also 250sho on local manufactured boats but they half the weight of the Cougar.I m off for the first time in August to run boat at sea level, hope to get full potential out of cat at last.Would love to know if you find the solutionJK