Our XK/R 4.2 and 5.0 exhausts are available in 3 stages of volume to cope with all tastes and requirements. All parts are made in the UK from 304 stainless steel, are mandrel bent for optimum flow and use OE style stainless steel clamps. The exhausts are available as a non active system for XK and XKR or as an active system for the XKR. With the active system depending on engine revs and throttle position two valves open in the rear silencer to increase both exhaust volume and gas flow. The benefit is its ability to deliver a better compromise for full throttle whilst maintaining quiet cruising and giving an improved note and better balanced flow.