deciding on a intake for a sbm weiand stealth or air gap

For what it's worth, the LD340 and LD4B are essentially the same exact design as the Weiand Stealth/ Action Plus, with the LD340 runner sequences reversed.

I compared a Weiand Action Plus to an LD4B, which are nearly carbon copies of each other, and discovered that the Weiand had much better quality casting, inside and out and the runners were slightly longer, giving the Weiand a little more height overall.

They are all good intakes and on a street car, will essentially perform the same, but the air gap is designed for cooling, so keep that in mind. Cooling is usually a good thing in high performance applications, but can hurt some applications with fuel puddling and fallout, due to intake temps that can get really low, if it's going to see lower temps. Intakes do need some heat to help atomize fuel for good economy and complete combustion, for good performance. Too much is as bad as having too little, so the reason to get an air gap would be from testing under hood temps to see if the car and how it's built, will benefit from one.

I'd buy an air gap if I was experiencing fuel temp issues that couldn't be resolved or under hood heat temps on an infa-red thermometer that couldn't be resolved.