Has anyone ordered / installed the Heated Seat Kit From GM Accessories (08 NBS)? GM P/N 17803282 The dealer wanted over $500 to install it, over and above the $399 kit price. I know it involves removing the seats, taking the seat covers off and installing the switches in the dash, but I am willing to do a lot of work for $500. Do the kits come with instructions? I am a newbie to this site and I have searched but could not find anything on this topic. Any info would be appreciated.