speakers, dash lighting, and electrical problems.

[Mteezy94]

I have an 2007 Silverado and my front left speaker thats next to the windshield (the "tweeter") it is distorted. I have had this problem before and they fixed it saying it was a common problem. Anyone know what it is and how to prevent it?

 

Secondly, I've been wanting to change the light behind the speedometer and such to Blue. How do I go about doing that? I want to get a royal blue lighting with a white needle set. I think that would look pretty awesome.

 

Last and probably most importantly. Pretty often through the day and more often through the night when the headlights are on, my trucks whole electrical system will flash on and off several times while going down the road (including but not limited to headlights, radio, dash, window power) , yet the car still runs, the subs still work, the speakers still work as if nothing has happened. The battery and alternator are fine. I had subs and a PA system installed which required wiring. I got it done by a really respected place, so do you think it could be the wiring?