My speakers are popping when I turn on the key

You are tied to the dealer on this one. General Motors has figured out many ways to bleed money from you after the sale. The high failure radio is one of them. To prevent you from buying a high-quality aftermarket radio, they began building the Body Computer into them. From talking with other people, the typical repair cost is around $450.00, and when it is returned from their grossly over-priced repair facility, it has to be programmed to your car before it will work. That can only be done by the dealer. Just one more reason GM is an extremely customer-unfriendly company and has been losing repeat customers.