I’ll agree that a street dominator is best for small port heads. They work best with 10:1 plus, a large cam, headers, 700 plus CFM carb, and low gears on a stock headed 318. But if using 308 heads with template porting and gasket match work (about as far as I would go in this heavy weight) an air gap is perfect. I’ve driven one on a N/A 9:1 360 with a comp 268 magnum and headers on an 8,000 plus pound 4.88 geared W300, and it had reasonably good torque even with the close ratio NP435. Depending on how much boost is being produced, 3.55 to 3.73 gearing may work better by keeping the turbo spooled up under load at its efficiency peak for more time. Water/Methanol (washer fluid) injection and boost timing master is your your friend if going with this plan. I’ve seen it work very well injected into the inlet of a ProCharger, I would imagine it would work pretty well for a turbo, too.
