Originally Posted by Too Many Projects
Is there enough difference in street performance between these 2 intakes to justify spending almost twice as much for an used air gap versus a non-air gap...
In a word- no. The non air gap is within a very small percentage of the air gap, and the major reason for the difference is not the air gap but the sliced out plenum divider that gives the air gap a slight advantage at the top of the rev band- where the engine is at a very small percentage of the time unless the vehicle is race-only.
If you plan to drive the vehicle in a cold climate, the air gap is even less of an advantage. It takes longer to warm up and the choke on the carb will be needed for a longer time. That can increase emissions, hurt mileage, and wear the cylinders and pistons/rings faster. This is slightly less of an issue if Vortec heads are being used; they do not have any heat cross over to warm the plenum anyway. But the splash from the lifter valley isn't able to help warm the intake on the air gap intake, so it's still gonna take longer to stabilize temps using the air gap on Vortec heads.
BTW, the air gap and non air gap RPM intakes are the same height.