Lemain. The Hunter had the 'Gun Dip' system fitted to alleviate the engine surge problems associated with the disrupted air intake flow during gun firing. This system has indeed been deactivated on all of the civilian Hunters.
The Hunter also had a means to isolate the twin HP fuel pumps to maintain a fuel flow in the event of HP pump failure. This was activated by a guarded switch in the cockpit behind the throttle. This High Pressure Pump Isolation Switch (HPPIS) could result in a considerable over-fuelling of the engine, the consequences of which would be an almost instant over temp/destruction of the turbine. It was concluded that the engine failure of G-HHUN was caused by the pilot inadvertently opperating the HPPIS when trying to activate the aircraft's smoke system.
It was yet another Hunter crash which killed it's very, very inexperienced Hunter pilot.