No point in propane on an engine with fuel injection IMO.

Propane really shines for the guys who don't want to mess with putting EFI in an older rig, the propane carb just bolts on and doesn't have any problem running at extreme angles like a gas carb does. Propane also gets awful fuel economy.

 

Back in the late 70's and early 80's propane enrichment was popular the the camping community. You know, the guys that were driving around in the 1978 Suburbans getting 8 gallons to the mile towing a 28' Holiday Rambler to the campgrounds and all across America. They would use propane enrichment as a means to cut fuel costs. The MPG increase was minimal so, I guess that's why you don't hear about it much anymore. My wife's grandfather had the setup on his truck and explained it to me way back when but I really didn't give a crap, I was running Big Block Fords suckin' up gas like I drink beer.