Depends on how efficient the carbs are but we have usually seen closer to one bleed being more in line with moving the jet 3-4 sizes. But your results may vary. My opinion would be don't get to carried away with dropping the hi speed bleed, and we are talking just replacing the high speed bleed here. They also sell larger jets than 99, and not all jets are created equal. You could buy 100, 102, 104, 106, 108 and 110's. But honestly buying a Holley jet and not pinning it who knows