...In the O'fallon Missouri area. Anyone here know any good Chevy
dealers? Preferably one friendly towards mods (not that I intend to do
any in the near future), and might be willing to install egt and boost
probes for me (for warranty reasons). I would like to get them in soon
as I'll be pulling 12-14k in the not too distant future.

Try Maczuk in Hermann Mo. Talk to Luke.

Also if you get up towards Blue Springs, Mo. see Randy in commercial trucks.