Presumably you don't get the problem in the car, becuase you never get close to 0.0db ?

If you've got your amplifier gain levels properly adjusted, you should get very close to 0db quite often. As long as everything's set up right, you should not get clipping. See the Installation section of the FAQ at riocar.org for details.

When is the next beta expected by the way ?

When It's Done (tm), of course.