while this is not a W-body but it is an interesting observation... this is a before video of a basically stock tune nothing but getting the trims away from +11 and closer to 0 but still fought 4* of KR on that tune till I found the issue.
then 3 weeks and dozens of tunes later at the same on ramp this is the same truck and similiar weather.
The only mods on the truck is headers bigger dual dumped exhaust and TB spacer and smoothed and blended TB removed restrictor and 4 in tubing and cone filter and egr and evap and bed cover.
The tune in it currently has changed the shift points from 25 mph to 40 mph in first and 65 to 80 in 2nd which the built trans seems much happier with. TQ management has been all but removed and ironically that is how the KR # have steadily came down and held down. I have added up to 10+ degrees of timing to the base map and see 40+ at cruise. The fueling is finally close and is usually +-2 or 3. figured even though it is not a regal it is a good case for indiviual tuning and what can be accomplished when enough time and energy can be put into a vehicle and its tune. if you have any questions i will admit I am no expert but slowly picking it up as I go and this is the only before and after I have that is really noticeable. mid range and part throttle are still not quite dialed in but they are getting closer and the seat of the pants dyno likes the improvement.
78 TTop TA w72,78 HT 4spd TA w72, 97 ws6 ta
03 regal gs 97 gs,06 gto, 93 blazer,98 k1500