Hi, I have 2000 EX V10 4x4 with LPG conversion. This is a LPG injection system, witch is hassle free. It always starts on gasoline and switches automaticly from gasoline to LPG at a preset engine temperature. This keeps the original gasoline system fresh by running a little bit every day. The system is made by a Canadian company called Ecofuel, and mounted locally. I live in Norway, and here, the price of LPG is close to 1/3 of gasoline. The truck use about 12-15% more fuel operating on LPG, compared to gasoline, but the fuel expence in real money, is like driving VW Rabbit.
This is my third LPG vehicle. Before this one, I had a 97 Chev Astro and a 97 Suburban. As you can see, I am (and certainly my wallet are) very pleased with driving with LPG.