I have used the RPM Air gap on a few different combos. I was very pleased with the performance from it. I used it on my 340, and the total combo had a nice power curve right to 7000rpm. We have also used it on a 434ci. It STILL worked to 6300rpm on that engine! I was quite surprised!

I have not had any personal experience with the performer RPM, or the Torker II. From the looks of it, the performer RPM has the same runners as the air gap.

however, if you are set on running a single plane, the Torker II would not be my first choice. From what I have seen on here, and I will be testing personally, the victor manifold is a much better single plane intake. Last year, I ran a Super Victor, and I was quite happy with the performance from it as well.