Spencer, current HOT ROD magazine has a tech article about the Vortech systems. In that article they stated that the dual plane worked well with blowers up to 5000 rpms. Above that the single plane manifold made much more power.I will see if I can put the article up for you if I can find it.
BTW, I am running an Edelbrock Air Gap RPM Performer with a Quick Fuel double pumper setup.It's hot here now and when I go to start the car when it's hot and been sitting a couple of minutes it starts after too much cranking and acts rich for a second.m I am sure it is percolation of the fuel from the ehat. The AIR GAPs do get hot if you drive for more than 30 minutes. I beieve raw gass is being boiled out into the manifold. My problem is that the manifold it pretty high, the carb and ari cleaner leave no clearance for my 1" phenolic spacer.It has four throttle bores exact same siZe as throttle plates. I am trying to figure out a way to use that spacer without changing manifolds back to the ZZ4.