ok so i bought the Maestro RR, GM5, and the AVGM5. The maestro came with a usb cable to connect to my computer to flash it and i bought everything that is available that was recommended the only thing i didnt get was the SPGM5, the audio place i went through said they cant get that yet. not like i really need it. all it is, is a speaker for the chimes instead of going through the factory speakers. everything works perfect and it was nice i was able to flash it to my impala radio because the radio i ordered the avh-4000NEX just came out and it will not be here until friday and i just cant wait that long with no radio and then when i get it i will just flash it to my new radio!!