Car Stereo noise (Not Audi specific)

[christopher_bender@fmc.com (CHRISTOPHER BENDER)]

     I have a 4000Q, and I installed a high power separate component stereo 
     system.  The system works great, but there is a whine in the back 
     speakers, that is related to engine speed.  
     
     I have a head unit in the dash, CD changer in the glove box, one amp 
     in the trunk, and another under the rear seat back rest.  I have two 
     6x9 full range speakers and two 10" subwoofers in the rear dash, which 
     I made custom out of a piece of plywood.  I have speakers in the front 
     dash and in the front doors.  These are Infinity Kappa Series with 
     their own passive crossover.  So I have eight speakers all together.  
     Oh, I have a active cross over in the trunk that splits the rear 
     channel between rear full range speakers and subwoofers.
     
     I experimented with different locations for the ground connections 
     with each of the components, with varying degrees of success.  I 
     conducted "experiments" by running wires over the carpeting to the 
     locations to be tested.  At one point I found a configuration that 
     gave me a noticeable reduction in noise, so I went to "hardwire" it 
     (install permanently with the wires under the carpets), and when I 
     finished, then it was noisy again!!!  Urgh!!!!
     
     Anyway, most recently, I replaced my US spec headlights with some high 
     powered Euro units which I wired right to the alternator hot lead (I 
     use relays to activate the lights), and I noticed a change in loudness 
     of my stereo whine when I switch from high to low beam.  I know my new 
     lights draw more current, and that, perhaps combined with where I 
     attached the power lead, could be affecting this.
     
     So, I guess my question is, does anyone have any ideas?  How about 
     those capacitors you can buy at Radio Shack that you put on your 
     alternator to reduce whine?  I haven't tried one yet, but I wonder if 
     anyone has any experience with them.  Does anyone know of an internet 
     group like this one for car audio enthusiasts to whom I might present 
     my problem?
     
     I theorize that I have a ground loop problem, although the noise 
     source is probably still the alternator.  A buddy of mine once 
     mentioned that grounding a car stereo is more of an art than a 
     science.  Does he have a point here?  Maybe I should just keep 
     experimenting, and not give up, but it is certainly frustrating!!!
     
     Thanks in advance to anyone who can offer me any suggestions.  I am 
     kinda at the end of my rope (er uh, is it my wire?).
     
     Chris