I know a guy who did this on a small pick (4 cyl) that had injection, and it worked great. Basically the injectors are for the gas and a seperate unit just just before the intake man acts as the lpg "carb". The unit is a kind if atomiser with engine coolant plumbed through it to keep the lpg from freezing everyhting and also to help the lpg turn to gas. around here licensed guys have to do the installation. With the electric fuel pumps of a inj sys it's a dash switch to go from one fuel to the other. Apperently you get a good burn with this type of set up, contact a lpg specialist they'll know. It's amazing how the oil stays golden forever when you run on lpg. Good luck.