I see a shop in Garland Texas (ExaTorq) offers dyno tuning using Wester’s Garage or HPTuners. Both appear to support the LY7 V6 in my 2005 CTS, so I emailed to see if I can arrange to have the CTS dyno tuned. Another 10-15hp would put the CTS low times for 0-60 mph consistently under 6 sec, which is my goal for the CTS.
Last test results, during the AP-22 side by side with the Performancebox report here.