Quick question is there what material best insulates cables from interferance i my tweeters make whistling noises
have the RCA on one side speaker cables on another and power in the middle of the car but still get a whistle even if just ignition is on

i heard foil but yeah i dunno
thanks

Please be aware i dont know that much before you flame :

 

The noise is probably coming from something else, possibly an electric motor. Try moving the cable until the noise is gone.
I used plastic shrouding to insulate all my wiring, works well.

 

plastic shrouding ok

give that a try thanks

 

move your ground that maybe will help