I think trying to increase cfm is irrelevant. increasing venturii area may help. thinning the boosters may delay main circuit discharge. you really need to think about what 800cfm is, what it will feed, and keep in mind that cfm ratings in real world applications don't mean that much. the carb is rated at 800cfm at 1.5"hg pressure drop. attach a vacuum gauge to the carb or manifold the next time you make a pass and see if your any where near 1.5"hg at WOT, then make an informed decision about what to do next.