This threw me for a loop at first, then I realized that you were doing the Instrument Cluster Actuator Test, and not looking for DTC's.
The first set of numbers/letters is the actual DTC for the inst cluster, the second set of numbers is the number of times the key has been turned since the code was set.
So here are the answers to your codes:
06 - MIL indicator output circuit open - 44 key cycles
23 - Headlamp switch input circuit open - 91 key cycles
27 - Courtesy/Dome output circuit shorted or open - 1 key cycle
29 - Cargo Lamp output circuit shorted or open - no key cycles
a3 - Battery voltage open - 44 key cycles
Knowing that you JUST had the dealer put your cab lights on a week or so ago, I would SPECULATE that they MIGHT have honked something up. I would definately get it checked out.
Hope that helps,
Andy
*EDIT* I see you jumped a few ponies since the last time I looked... What did you add to get to almost 100 extra HP? Did you add a box?