There's no benefit (or at least no discernible performance advantage) of using a volumizer on the LPR side - the constriction that takes place in the central LP air line and the teeny tiny channels of the manifold and solenoid defeats whatever theoretical positive effect there may be. It's just an excess void. The MTs actually recommended against using them on the LPR side. I like to use a small volly on mine just because it's easier to remove for maintenance and adjustment, but it's functionally useless in terms of performance.
The big brag with the SCMIII and JDS LPR is that they are pressure compensating, meaning that theoretically, they maintain a consistent output even if your input pressure drops off or spikes. Their recharge is also very good, and external adjustability is convenient. Bear in mind though that you will need to use a DIY LPR gauge that you will attach to the central LP air line at the rear of the gun to set the pressure accurately. To make the gauge tool you will need a M5 to 1/8" adapter
and your choice of 1/8" gauge (0-100 psi is a good range for the LPR; make sure you get one with a face that is easy to read). Using blue loctite or PTFE tape as a sealant, attach the gauge to the M5 to 1/8" adapter. To use the gauge tool, you will need to remove the grub screw from the central LP air line in the rear of the gun just beneath the solenoid housing. The grub screw is secured with red loctite from the factory, so you will need to use a lot of heat and go slowly - it is very easy to strip the hex head of the grub screw. Because of the heat, it is a good idea to remove the solenoid and ram before proceeding. Once you get the grub screw removed, you will screw the gauge adapter into the gun in its place. Clean off the old red loctite from the grub screw, and when you are finished using the gauge, reinstall the grub screw with blue loctite so that it will be easier to remove in the future.