As you're going for consistency this is nearly impossibly to do. As soon as you WOT it, it is going where the converter flashes anyway. Doing it twice for a back to back comparison consistently would be unlikely. How long are you at WOT under 3500 RPM anyway?
I've got a Mustang dyno and I can do part throttle dyno pulls as well as WOT, which would be useful for really comparing the intakes. I've even got a 318 powered plymouth, but it currently has a Holley Street Dominator on it.
I am very curious to know if the LD4B is really better than the Performer, and I want to know if the LD4B is the same thing as the Weiand Action Plus, but I'm not spending $750 on intakes to find out. haha.