Brad: In my experience , the answer is no, they actually improved.
Caveat: we are talking about 4150 flange carbs here.
Ours improved again after Wilson had everything and, could have been better according to Wilson but we are space limited for using a carb spacer, Wilson used all the room we had and its just under 5/8.
But moving from the Pro Systems 950 to the Twin gave better plug readings as well as power.
My thoughts as to why there might be distribution issues is pretty simple: I look down from the top of the carb and I see a potential "dead zone" in the gap between the boosters for a single blade. It would be interesting to see extensive velocity probe readings from the same intake manifold being flowed with both a Twin Blade and conventional 4150... even better would be comparable CFD analysis.
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What work did you have Wilson do, and on what intake manifold? Pics?
