Anyone can make good power in perfect conditions. It takes real tuning talent to make it happen on regular 91 octane Arizona pump gas in the middle of summer heat soak. This Mercedes-AMG GT63 rolled onto our dyno and put down 711.9 HP and 744.6 lb-ft to all four wheels, and that's the real test of a quality tune: how it performs when conditions aren't ideal. That's what g ood calibration looks like: a Weistec W2 ECU and transmission tune doing its job even when the fuel and t