Conclusions
Edelbrock claims a cooler inlet charge with the Air-Gap design, which uses an open valley beneath the plenum and freestanding runners. We did not data-log temps, but we suspect the cooling effect doesn't make a lot of difference in the dyno room, where the engine is not very hot to begin with, and there's plenty of airflow across each intake. We think there are minor differences in the plenum volume or port shapes that create small power gains with the Air-Gap. But we could be wrong.
Bottom Line
The Air-Gap is always a top performer, and it looks cooler, but you can save the $24 by purchasing the regular RPM, and you won't go wrong.
Read more:
http://www.hotrod.com/techarticles/..._not_edelbrocks_rpm_vs_air_gap/#ixzz1oBImNrLT