Twin 496 mag HO'S starboard battery being drained after sitting around in the garage with everything shut off. I just replaced both batteries last week and this did not fix the issue. I have also noticed that when the silent choice exaust is on the volt meter drops too 10.5 even on fresh new fully charged batteries. Then when I shut the exaust off it pops up to 12 volts. There are so many wires and connections I don't know where to start to look. Any thoughts would be appreciated. Thanks

The voltage on the port side drops when I turn my SC on also. Seems to be the nature of the beast.
As far as the battery draining, get a voltmeter and see where it is drawing current.
Remember that you will have ~ 22-25 ma of current going to the motors even with the selectors off.

Where do you think a good place to start would be?