Blues,

To be honest I have a TON of work in that manifold and it works awesomely so I doubt I will be turning it loose.

I'm not really sure what all the fuss is about with the 337, if you go to the tech Archives on Firefighters 572" (!!!) motor the Port matched (but still unported) 2d was only down 4hp (717 to 721) and 7 lb/ft (697 vs 705) to the 337, that's hardly a runaway victory (about 2/10th of 1 Per Cent) in my book. Dyno numbers are one thing, but roll-on part throttle torque (ie, "real world driving" is is almost always going to favor a 180 dual plane.

on a 750+ hp high RPM motor I would expect the difference to be more dramatic but up to 700 and especially with an automatic I don't think I would call the single plane a big (or even a noticeable) advantage, and at 470 to 500" I would think the advantage might likely be less noticeable or may actually be in the dual planes favor (in terms of average torque)

In my own case now I have a fully ported to fully ported comparison, I want to spend a day on the Chassis dyno and then hopefully Z-max at a Test & tune, but that will likely be after I swap back to the 833 4 speed. Ootb I didn't feel the 337 would have had any appreciable advantage over the max ported 2D so I never was too motivated to swap it.

It's not readily apparent from the pics but Larry did a lot of whittling on the 337, it should work really well. The ports are a good bit larger than before the walls between the runners are a good bit thinner, it's not just a polish job by any stretch for sure.