Did you install a set of Type R coaxials or components? (if you're unsure of the difference a component set will typically include a tweeter, a midwoofer, and a passive crossover module while your average coaxial is the woofer, mid, and tweeter [or however many elements it may be] all built onto the same frame with no outboard crossover)
If you've done coaxials I'm noit understanding the reference to the tweeters in the doors? Have you installed speakers plus some auxiliary tweeters?
And is the amplifier a 2ch or a 4ch?
What iluvslp was attempting (I think) to say was that your problem sounds indicative of a ground loop problem. You're picking up RF interference from somewhere (could be the alternator, could be old or poor quality plug wires, could be from the coil, could be from many different potential sources) and yes, it will fluctuate with your motor's RPMs.
This problem is almost always a bad ground somewhere and from what I have read above you've eliminated the amplifier as a possible cause. The exception would be something being faulty within the amp itself (and unfortunately with a Pyramid unit that's not unlikely)
