not methane... methanol/water injection. Many alcohol-water injection systems use a mixture of water and alcohol (usually 50/50), partly because the alcohol is combustible and will raise the octane level of the fuel. While water is not combustible, it has a greater capacity to cool the intake air temps down more than methanol alone. This effectively increases the octane rating of the fuel allowing performance gains to be obtained when used in conjunction with a supercharger or turbocharger, altered spark ignition timing, and increased boost levels.
procharger is actually a brand i think but it's more of a self contained centerfugal supercharger... it looks a lot like a turbo, but it's belt driven
by contrast this is an average supercharger
and a turbo charger with the compressor... the exhaust gas goes in the darker gray snail thing and spins the impeller which spins the shaft to spin the impeller inside the shiny snail... that impeller compresses the air which is forced into the intake...
a remote mounted setup is when you mount the turbo under the car, usually towards the rear of the vehicle directly onto the exhaust pipe. then the boost is piped back to the intake. some people feel that the long length of chargepipe casues mad lag, but there again, depending on the tune and the turbo, it can be very effective, especially with larger displacement engines. it's a great way of making a sleeper casue you can't see the turbo unless you start looking for it.
twin remote setup
as far as propane injection goes... i am not sure but i thought that was for diesels... although my dad used to have an old ford truck that he could hit a switch and switch completely over to run on straight propane.