340 has no balls

The port mismatch in going from a smaller port to a larger port is less than ideal, but doesn't cause nearly as much turbulent weirdness as going from larger to smaller. It's a similar instance of the Bernoulli principle as occurs in the venturis in a carburetor (albeit not as smooth). It may arguably be somewhat beneficial in some cases due to keeping reversion pulses from setting up in the runners.

I'm betting on the slipped inertia ring on the damper. I had one that ended up being off by 16 degrees and it drove me crazier. I hope it turns out to something something that easy to fix.