I did the Mercedes diesel to International Travelall conversion. I have the boost cranked up to 13.5 psi. I intercooled it using a intercooler from a ford probe. The propane is set to inject when I hit about 5-6 pounds boost. It is controlled by a adjustable Hobbs pressure switch which screws in to the intake manifold. (Theres a plug near the rear you can remove and srew in switch). I also have a manual overide button that I use to give me propane earlier, such as coming off a light with a grade and boost hasn't built up yet.
The instalation is nothing more than a barbeque propane tank with an adjustable regulator, like an acetylene setup. LPG grade hose which runs to the firewall where you use a 12v pressure fuel lock. I got mine from a place that runs there fleet on LPG. From there you run the hose into the aircleaner. I used a fitting I had like an air hose coupler. The wiring basically controls the 12V pressure switch. Energize it an propane injects. THe closer interlock switch is to the aircleaner the better. You get less lag when you hit it. THe adjustable regulator is set to about 1 1/2 lbs
THe power difference is UNBELIEVABLE!!!!!!!!!!
Propane is 118 octane. If you rev the benz to 1000rpm and hold it there and hit the button, the motor goes to 3500 Rpm instantly!!!!
AS far as safety issues I am not going to get into it. My vehicle I have it in, now resembles a 4 door pickup so my cylinders are mounted ina compt that is now technically in the "BED" portion..
Could you mount it in your trunk, sure I guess but a safe vent would be ideal. It is up to you to decide how and where to mount the tank. Keep in mind that there are alot of propane/Nat gas vehicles on the road that come with the tanks mounted in the trunk from the factory.
THe mercedes motor accepts propane wonderfully. I drove that truck to Carlisle PA from LOng Island and the "juice" was on most of the time due to the hills. Drove there and back and didn't even burn up one tank. I think its the best thing since sliced bread.
Good luck Mike Moran