300K mi. 2016 Silverado 2500 Tuned on the Dyno | What happens?

Today, we put a 2016 Silverado 2500 with a 6.0L engine on the dyno for custom tuning. This truck has clocked over 470,000 km (300,000 mi); despite this, it showed acceptable baseline numbers of 212.71 lb-ft of torque and 193.02 horsepower at the wheels. This high-mileage engine ran smoothly during the initial runs (up to 5800 RPM) with no pings or knocks, but it felt sluggish in the lower RPM range. The data confirmed this, showing the torque curve dropping rapidly at around 3,000 RPM. This is typical of GM trucks, which often have factory tuning that limits low-end torque. Our goal was to fix this issue to give the truck more power where it's needed most—at the low end. This improvement helps not only with towing and hauling but also with fuel efficiency when accelerating. After adjusting the air-fuel ratio (AFR), we made additional dyno passes to set the cam and ignition timing, producing a stronger and smoother torque curve. The results were impressive: torque now peaked at 312 lb-ft at 2,100 RPM, compared to the initial 188 lb-ft. Overall, we showed a torque increase of 61% from baseline at peak. We also adjusted the transmission's shift points, ensuring smoother shifts at the correct RPMs. This change helps the high-mileage transmission handle the added power and continue to perform well over time. Overall, this tuning session gave the Silverado a big boost in low-end power and improved its overall performance, all while keeping the reliability of this well-used truck intact.