[redpoint5]

In my pursuit of fuel efficiency I have overinflated the tires on my TSX to ~45psi. Now, the TSX is an entry level sport-luxury car, but the cabin has always been relatively noisy. With the increased tire pressure, road noise is even more pronounced. The only mod I can think to do that would lessen the noise without adding weight is active noise reduction (ANR).

1. Can this technology be implemented in a vehicle application?
2. Are there stereo head units that support ANR?
3. Do you have any experience or advice concerning ANR?

Ideally, the system would use the existing speakers in the car and play nicely with the factory installed radio. Is it ok to have 2 separate sources connected to the same set of speakers? That is, can you connect 2 stereo head units to the same set of speakers without fear of damaging the output amps of the head units?