Congrats on finding an 07 LBZ. You and Father in law will come to love it as much as I love mine...(06 lbz)
cpl of suggestions for mods...nothin crazy but stuff that will help maintain the motor and Tranny in perfect shape.
EGR blocker plate
; Why put soot into your motor..?? Block it and if the Edge does not take care of the CEL, you may want to invest in a "fingerstick" - a small module that is inserted into the wiring harness to fool the ecm into thinking the egr is working as designed...some say there is a slight increase in mileage.
Secondary Fuel Filtration
or Nictane or even Stanadyne have great systems and filtration down to 5 micron particulate size. Why..well it is the particles of 5 -12 Micron that do not get picked up by the OEM fuel filter and are the ones that can cause issues with injectors and injector pump. I'm running a Stanadyne FM100 fuel manager w/5 mU filter (2 mU is available as well) The systein my truck is post
Secondary Oil filtration
: Its been noted that synthetic is a better solution for lubrication, I agree..but the cost is typically 3 times that.! To make Synthetic pay for itself it is, IMHO, a very good idea to go with what is called a bypass filter system: a line from the motor goes to a cannister with the filter media in it (typically 2 mU)..then goes back to the oil pan. Typically I get between 15 and 18,000 miles on an oil change. Oil analysis will prove time and time again that this type of set up works and works very well. On my truck I use an FS2500. Sits underneath the drivers side rail. The filters run around 25 per...unit ran me about 450 USD (6 something in CAD pesos..!) I believe that Amsoil also has a similar system and there are others out there as well.
Synthetic Trans Fluid
: For the allison, best thing you can do is change the red spin on at the same time as you do an oil change..(dont forget to re-install the magnet there.!). If you can do it, switch to Detroit/Allison Recommended - Castrol "Transynd" Synthetic Transmission Fluid. Your tranny will run somewhat cooler and you will likely increase major service times from 25,000 to likely 100,000 miles.! Great stuff.! antoher pretty decent mod is adding a TRansGo Jr Shift kit..beefs up the tranny a bit and can likely handle an extra 80-100hp..anything over that and your lookin at a built unit or at least some serious clutches.
Cheers and warn your Father in law to watch his wallet...Dont ask me how I and so many others happen to know that..