this is the job of the installer..period!!
normally wiring installation issues most of the time..

sent the car back to them..its their job. cant rectify or cant give reasonable reasons as to why, change installer.

note: solve the noise issues NOT hide the problem. this is wat people do most of the time. careful

important: dun add that stupid black color thingy to ur HU or alternator. IT DOESNT WORK AT ALL!!!!

the right way, find out where is THE NOISE COMING FROM!!! (basic car electronics 101)
then solve it from there. kow tim!