Now, the effect of the elevation is seen from the bone stock baseline which is 315 to the wheels. This is roughly ~40 wheel less than an E92 M3 DCT will make at sea level. The first graph you see here shows the difference between stock, with full bolt ons (tune, exhaust), and as it currently sits supercharged at 9 psi. With full bolt ons the car put down 344 to the wheels which is roughly a stock number at sea level showing just how big of a difference Denver's elevation makes:
He's taking a roughly 8.5% penalty in power. The nice thing about being supercharged is he can compensate for this by changing the supercharger pulley effectively spinning the blower faster. He tried three different pulleys at roughly 6, 7, and 9 psi of boost. That result is below:
524 wheel with the standard pulley in the ESS-VT2 650 kit, then 565 wheel horsepower dropping down a pulley size, and then an awesome 613 wheel horsepower going to a pulley giving 9 psi of boost. He compensated for the elevation and then some.
Awesome graphs overlaying the difference. Thank you very much to @BlownE92M3 for sharing. Dyno video below.