Oddly enough - the interference is like x3 times worse with this new PSU - but on the bright side I'm assuming it's all coming down the the PSU causing the issues. It comes in at 5.20V at the jamma pins.
Is there anything I can do to the PSU's to help clean them up? Maybe add in some sort of filter, or should I just stop right now and get a different PSU with the ability to adjust the 5V? (and if so which one would you recommend for a consolized MVS1FS)