Heads for mild 360 build

STP...... standard temp and pressure.
The SAE J607 correction
Net observed power corrected to what you’d get at 60* air temp, 29.92’ baro, and zero humidity.

This is the “corrected” power from the dyno you see in magazines, etc.

At 5700’, you’re quite far from those weather conditions, so the motor will make considerably less power.
Thank you. I have tuned cars in Colorado, and yes there is a substantial loss of power in that altitude.