I have two Rockford Fosgate amps and a 1 farad cap, although I have tried to isolate alternator whine I still get some noise, but not really noticable with the player at -30 db. One thing I have noticed is that the riocar seems to isolate some noise on its own as well. I have less noise with the rio, than I did with only my kenwood deck installed, maybe the player or maybe some wiring changed. I would imagine some noise is normal. Im curious what is normal or acceptable noise level with a "good" install.