I have a 2008 G8 GT with Kooks long tubes, solo catback with no cats, VCM otr intake and after having some false knock issues and also no experience with the 6l80 decided to take my car to one of my local LS specialist shops to have the car dyno tuned. The car is running great and the owner did an awesome job on the tune. The trans shifted nice and crisp in drive and had a noticable increase to the firmness in sport mode soon after the tune. As time had gone on the part throttle shifts seemed to get softer and lazier unless I got into the throttle a bit and for a while the shifts would go back to quick and crisp. I started to compare the new tune file to the stock tcm tune as well as some others on this site. Looks like they only went shorter on the shift time in sport mode, went slightly higher on the base pressures and also double the oncoming pressure presets in drive and tripled them in special. I was thinking of putting the tcm back to stock and starting over. I've seen a few threads where recommendations were made to decrease shift time by say 20% and increase base shift pressure by 20% but never really touching oncoming pressure presets. Would you recommend starting from scratch or just moving forward with changes with the current tune? Attached is the current tune on the car.