Late last year, we were invited by a Jaguar dealership to read the data in the Jaguar XKR-S ECU (engine control unit). After comparing the data between the 470hp, 510hp, and 550hp there are certain limiters written in the factory software that affect each model differently. By tuning the ECU, those limiters which have been discovered will now be removed. In conjunction with the regular ECU tuning (speed limiter, hesitation/flatspots, etc.) the new software uploaded into each vehicle will be from the same specifications of the new XKR-S. The only benefit other than hardware from the new XKR-S, is the factory upgraded exhaust. By completing the ECU tuning in the XKR-S, utilizing the factory exhaust system, we can take this car to 605hp with just the ECU tune and pulley. Customers who wish to see similar results, we recommend purchasing a Quicksilver exhaust.