Step, by step, we're getting closer
 

Thanks Stephen,
The good folks over at Facebook kindly sent the same info along. I appreciate the help.

Update: Thanks for all the great replies and PMs! Heading for Phoenix for a marathon in two weeks and have an appointment with the local GMPP dealer there to put the upgrade kit (thanks again for the link to GMPartsDirect) in the panel. Fingers crossed; I'll report back on the outcome.
John

Maybe you should just keep going and head in to Dallas and get ChevyMgr and his boys to do it. You did emphasize getting it done right.

Tireman,
Just proves the notion that there's always a better idea! Talked to the Service Manager at the GMPP dealer and he says they've done a lot of them but I'm being pointed to "Steve" the tech and if he scratches his ear (or anything else) just once, I'm off to Dallas.
Thanks.
John

Update! Thanks to the good folks at Courtesy Chevrolet in Phoenix, the Stage 1 in! Unfortunately, the service tech who knew how to do the install blind folded quit a few weeks before I got there so a new guy did the deed. Only took him 6.5 hours including removing and reinstalling the radiator (the guy had huge hands and couldn't reach the lower TMAP) but the dealer keep to its estimated price so what's an extra 4 hours? Actually, the guy did great work - harnesses are perfectly placed and secured, he would have done 1/2 hour sooner but he keep opening the hood to make sure everything was perfectly dressed. Thanks to everyone for the helpful hints, copies of TSBs, and encouragement. Left the dealership and drove back to LA a whole lot faster than I got to Phoenix! So, what's next?