And OMG you dont need to spend anywhere near 4Gs on a twin set up.......try half that

I see what you mean about the $4k! Those Revolution replacement manifolds look pretty impressive for the $$. Has any one used them?

I have the Rev Marine manifolds on my 406 SBC. -- Picked up aprox. 300 rpm as compared to the stock manifolds -- all else being the same. Big weight savings as well. -- could feel it in driving the boat.