Mine was changed last week and the results are similar to glc's except that where the reception was horrible or lost it did not improve. It is better overall. This is in hilly north central Ma.
I was just at my dealer in Ma. and talked with the service manager about my radio so he checked on PI 1288 and discovered that GM issued PI 1288A on Fri. Sept. 5 which includes replacing the hardware. My serial number is included so they are ordering it.