My experience with LPG is the same, blew the airbox to pieces after dodgy leads crossfired. Have since replaced with eagle 9.5mm leads and fresh plugs. According to LPG pros, the ignition system needs to be tip top on LPG. My system starts automatically on fuel I thinkl, 'cause I can hear the full pump running when switched to LPG and have never had backfire on start up, but then I don't touch the gas peddle. A mates blew to pieces in the middle of the state forest after his son went to move the truck, not happy. Thankfully I've not had a backfire since upgrading ignition. Bottom line is the LPG must go in favour of a 150l fuel tank.