in melbourne, vicroads rwc testing laws state that 10years from the date the compliance plate on the tank, your tank has to be ripped out and re-tested. liquid injection is the way to go if you are looking at converting to LPG. the main benifits are that, as the name states, the LPG is in a liquid form right up until it is injected into the manifold. yes gas does burn a bit hotter but gas also loves higher compression ratio's (14.7:1 for petrol vs 15.7:1 for LPG). last time i asked, liquid injection kits start at about $3500 i think (tho i was quoted by one of my trade school teachers who is on the AAFRB panel and is the authorised teacher for the LPG fitters course in melbourne) and that was for my b18c1 set up fitted & tuned. if you are serious and live in melbourne, pm me and i can put you onto the right people to talk to (not your everyday fit a LPG system with no license mechanic)