What's your cylinder pressure or compression ratio?
At 165psi, with a 268 or bigger cam, the AirGap is the go-to item.
At 155i, with a 268 The AirGap is starting to earn it's keep.
At 145 with a 268. The AirGap is fast becoming the wrong item
At 135 with a 268, the AirGap I would leave it in the box;this is a poor combo
At 125 and a 268, You're either ignorant, stupid, or rebellious;that is a crap street combo. Oh sorry, I didn't mean to hurt anyone's feelings,lol
Just don't put it on a smallport head, that's just wrong. The heads will tank long before the intake gets wound up.
See, the AG is sortoff a high-rpm manifold with excellent midrange capability. But the low-rpm performance will depend very heavily on the engine under it. Those big passages and the fairly large plenum want airspeed. And the teener cylinders are 12% smaller than the 360's to start with. If you put a big cam in it with a late closing intake, or if you start with an 8/1 compression, you are begging for disappointment. These combos make for slow low-rpm airspeed. And that leads to low-performance.
The AG on a strong signal, is dynomite, especially in the high rpms. But first, you gotta get there. And if the cylinder pressure is low, it's gonna take time. With 3.55s, and a 268*, it will be about 35mph before it wakes up, and 50 before it's hauling azz..And if the stock pistons are stil in there, then you are gonna need a big TC just to get rolling.
But with a 10 or 10.5 engine, and hi-flow heads,the 268* will love the AG.
It's all in the combo.