Good to know. Even without the engine rev'd my batteries (or battery rather, I have 1 of 2 C&D's installed right now) my voltage stays in the high 12's. Honestly I don't listen to my system full tilt for long enough periods to drain the batteries that much either. I usually listen to a song full tilt, then the next one I'll play it at a lower volume.
---------- Post added at 01:05 AM ---------- Previous post was at 01:04 AM ----------
Yeah it is a lot louder. Between dropping down to .5 and raising my tuning a few Hz I've gained an easy 3dB (at least by ear).