Well i just got in the Wet Sounds Bluetooth Volume Control. I have an AUX plug already in the HU so I guess I'll just hook that up and see how it sounds. Might end up skipping the 420 all togeather and the only reason I was looking at it was to control the volume anyway and replace the HU.

I see the reason everyone keeps telling me the put the 420 on the drivers side but i think everyone was missing my original idea. The whole reason i was considering the 420 was volume control.
Right now i have to get up and go the the glove box and change the volume. Hence why i bought the Bluetooth volume control now i can hook it up on the drivers side and not have to move to change the volume. If I get the 420 and put it on the drivers side then i defeats the purpose of buying the Volume control in the first place. But if I pull the HU and put in the 420 and set it just the way i wanted(base/treble) and not worry to much about the zone volume just overall volume then that all I was looking for.

Hope that explains my thinking a little better.
Let me know if you think I'll just be waisting my money by going this route and not taking full advantage of the 420 because the the zone volume control which I don't know that I would use as much.