Note - The comments I made regarding the 2x4 dual quad intakes apply only to the B and RB engines.
Additionally, in a quote from HOT ROD Magazine, it was said regarding the Offenhauser dual quad intake (Edelbrock makes one too for the RB only):
"Though its outright power isn’t up with the better manifolds, it does gain some credit for eye appeal in a low-rise package. If max output is your game, there are many better choices."
