I'm assuming those jet sizes are for the main? Going from a 122 to a 118 would only get you set to 4,000ft. I run a 110 main right now.well on my quad there is only about 4 jet size variance between high altitude and sea level, 122 for sea level and 118 for high altitude this thing is "supposed" to cover 8 to 10 jet sizes, but I doublt I will buy it I would much rather spend that money on a good aftermarket carb. mine is 36mm i want to move up to a 38 or 40 mm after i'm done with this head.