I have had a few audio upgrades done on my 09 XRS
Alpine IVA-W505 7" DVD screen
Alpine PMD-B200 NAV
Nakamichi PA-2004 amp
Image Dynamic CXS54 components
Viper 5900 security
Got all this installed by a shop (Visions Kamloops) just before a road trip.
Heard alternator whine the whole way on the trip.
When we got back the shop said they would trouble shoot the problem but tried to immediately blame the Nakamichi amp (which I supplied).
After swapping out for different amplifier (tried 3 amps so far) and trouble shooting for a whole day the shop tells me they think it's the Toyota alternator that is causing the problem and suggest I upgrade to an after market high output model.
Stereo upgrades...then trouble? - Toyota Forums :: Toyota Nation