I agree 100% with the single plane vs dual plane on a 408 with very good heads. My 408 in my street use Dart with a 4 speed runs 3.23 gears and a single plane manifold. There is no shortage of low end torque on these engines. I believe fuel distribution will be much better with the single plane. I street drive my 408 with a
[email protected], .580 lift cam with absolutely no driveability issues.