I put some Z71 springs in my old 03 LT Suburban. Didn’t have the air ride, but DID have the expensive Sachs shocks that acted as a “secondary spring” (stock coil springs could not be run with conventional shocks). I didn’t have to deal with the computer issues, but obviously, the spring swap was necessary in order for me to switch to Bilsteins.
It raised the suspension 1 to 1-1/2” in the rear. I bought some el cheapo front torsion keys off eBay that allowed me to dial up the front enough to match the rear lift. Local shop did it all for $200-$300 labor. Beat the heck out of me crawling up under it all day long.
The keys were $30 or less. The rear springs were less than $150 (3 years ago).
