I don't have the numbers, but quite sure the 441's will outflow and outperform the 906's.... What are the valve sizes in the 441's? There's some really sharp SBC guys (I'm not one) on here, I'm sure they can give you some good advice on how to get a bit more out of them without wrapping up a bunch of $$$$$ in them!!!!

Pictures of the Avanti, PLEASE!!!!!!!!!