I have looked into the propane kits a bit -- they sound tempting! I've also talked to a few people that have them and their experiences seem pretty similar.
They all say that the kits do provide a pretty good boost to performance -- which they like. But filling up with propane all the time is a hassle. And finding somewhere to put the tank is a pain.
I subscribe to Joe Donnely's philosophy: there's only 1 way to get more power, and that is to add more fuel & air. There is no magic "catalytic reaction" that makes power from nothing. With the propane, you are just adding more of a different kind of fuel that happens to work well with diesel.
For my money, the complexity and extra work of finding a place to mount the tank, and then keeping it filled, is not worth the gain. Our engines have a lot of untapped potential just using diesel fuel instead of going to something like propane injection.
I didn't intend to rain on your parade -- this is just my opinion after researching the propane systems.
On the other hand, you may like something like that just because it's different.
Dave
'93 D350
'82 Ford w/Deutz F5L912