I will spare the details, but been working on jetting for my altitude of around 4000'. I have a 1987 Mariner 2 liter 150hp 2 stroke. What does the Merc/Mariner manual show for the stock fuel jet size I'm assuming 80? What is the stock air jet size? By trial and error I have leaned the fuel jet down to a 76 & air jet I have increased to a 58 which is bigger than I started. I have had positive results so far, but before I go much further I want to find out what the manual says for sea level and higher elevation if they have such. My boat mechanic friend is out of town for a week otherwise I'd ask him. Thanks!