Holley, in their infinite wisdom, says a single plane works best with the EFI. Some say a dual plane works fine. Apparently there is a sensor that reads pressure inside the plenum. With the divider in the dual plane you're only reading pressure on one side so if you open a window in between it allows the pressure to be read on both sides( so goes the theory). Makes sense I guess. This was much easier than going to all the trouble of getting a new intake and doing all the port matching again. Besides I like the hp/rpm range it has with this intake. A single plane would probably change that.

I feel for you Al. It's bad enough when it happens to me and it only takes me a few minutes to go get something. Sometimes I just buy two of whatever because I figure one is probably broken( or going to break)/bad/wrong. At least then you have a 50/50 shot. You can always return it next time.