I don't know the flow numbers, but I would have to imagine at LEAST 25% more than a 65mm. Just bcause there is no restriction, like there is with the 2 butterflies. Put 2 silver dollars on a piece of paper maybe 1/4 to 1/2 inch apart, and trace around them. then draw an oval around the two circles, everything outside the 2 circles, but within the oval is blockage of flow...this represents the stock type tb. It's a decent amt of material to be removed with the single blade. I'm sure some mags like MMFF will eventually be doing product testing soon. To me it's like one of those things where you go " Why didn't I think of that".