Liquified Petroleum Gas is about 1/3 the price of Petrol and produces more Torque, But less HP(not noticeble though).
The conversion costed about $3,000 and has already payed for it's self. So now as long as LPG is cheaper than Petrol it's the way to go.
The major future problem may be excessive Valve seat wear, Even though the Kit included plumbing for Valve Seat Recession Oil.
LPG for Barbecues contains Butane and Propane, Where LPG for Cars is the Gas given off of Petrol during the Refining Process.