What he's doing is making the intake side and the manifold side of the carb bigger (I don't know exactly how it's machined), but he has tested them on a flow bench and the stock flows at 199 cfm's and the new bored out carbs showed 234 cfm's. He also does some drilling to the slides, and polishes the slide. I don't know why. The test will be if it feels better, more responsive, dyno numbers...

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