M1 or Port-Matched LD4B on 408

Edelbrock air gap RPM. A good flowing dual plane is the way to go on a street car.

Bunch of dyno pulls for different small block intake manifolds. No M1 unfortunately, but a modified Edelbrock Torker II is included, as well as an Air Gap. The Air Gap wins horsepower and torque below 5k rpm, then gives up a little of both from 5200 to 5800, then pulls up even again from 6k to 6200. I’d rather have the advantage down low than from 5200-5800.

Dyno-Testing Small-Block Intakes - Induction Extravaganza - Mopar Muscle Magazine