From playing around with my own combos-
[email protected] cams, and dp 180* vs sp 360* intakes...I see an rpm ceiling diff of around 350-400rpm, but the torque is like 40ft lbs more with the dual plane and where it's more usable in the range.
But, if you plan on rev'n it into 7k+rpms, R.O.T says single plane.
Combo's...they like what they like.
JMO