Thanks for responding gents Think my 2003 version only has 400 bhp but that's more than enough for now - limited top speed is 155 mph. Apparently 2003 XKR uses belt-driven Eaton rotor-type supercharger with intercooling, with helical rotor gears for low noise and coated rotors for maximum efficiency - at the time both industry firsts on a production engine. All the best, Phil