Your right, it wouldn't be easy but since there are no consecutive exhaust pulses into any of the siamesed ports headers could be (maybe) designed to get the approximate same flow between single and siamesed ports. Strictly a guess would be the primary tubes on the single ports would have to be BIGGER to drop the velocity and diminish the scavaging effect to that of the siamesed ports. It would be fun to play with this on a flow bench.
