Thanks for the update, Bill!
FWIW... I got the same story from my Freightiner dealer... no engine upgrades after the truck leaves the factory.
I kinda wish I'd splurged for the 330/1000 option when I spec'd the M2. Oh well.
Did you find out if any changes to your Allison 3000TRV would be required if you upped the engine's peak torque?
As a cheaper alternative to the VMS unit, consider the
CANTrak. I don't have one yet so I don't have any user experience to share. But, the price is attractive at about $400.