I have a 96 Landrover Discovery on dual fuel, at 16l/100km it was sending me broke, I always start the car on petrol as it is injected and the LPG has a long runner to the heads so it takes forever to start on gas. Switching from petrol to gas is instant but going from gas to petrol you have to wait for the gas to run out. I can't pick any difference in power between the two fuels, but at 3.9l hauling a 2.25 ton there isn't much power anyway, she sounds good but doesn't do much. When I had it converted, it only cost me $500.00 after the rebate so the cost has been low. I'm very happy with it even though the car is a bit fragile as a daily driver, it is now used as my tow vehicle as I travel to work by train and I have my VE for normal use. The tank is behind the rear seat and holds 110l, I didn't want the scuba tanks they put under the rear of the vehicle as they cut the petrol tank in half when they install it like that. If you are going to install lpg in an HZ van, I would recommend fitting the tank on the left side of the vehicle, opposte the exsisting petrol tank and having the filler at the back next to the tow bar. My father had this set up in his HZ van and it didn't require any body mods and the spare was in it's original location.