Whomever you talked with misled you. The diameter is not the final factor in the flow rate. Thats why some jets with different numbers have the same diameter. A lot of bad info out there - and some of it comes right from the manufacturer's "tech" people. :( The carbs that were decent to begin with are within a few jet sizes no matter what they get put on. Its the beauty of a carb - they respond to engine demand so supply what the engine wants.