Okay I ordered a mechanical fuel pressure gauge that I'm going to mount in the engine bay. I thought it would come with a line or something to connect it to the fuel rail but it didn't. I did some research and knew I would have to find a -4an to -6an fitting or something like that, but what else do I need. What type of line do I get to run it? Sorry for the dumb question, I've never installed a gauge before :)

uhm, i don't know about you but i would NOT install a mechanical fuel pressure gauge. if theres a bad accident, it may spray fuel in the cabin (not a good thing). i think there was a recent accident in nhra where the dudes mechanical fuel guage got ripped apart and caused a fire. autometer sell electric fuel pressure gauges and i also have dynotunes electric digital fuel pressure gauge. if you do use a mechanical fuel pressure gauge, use it to tune, then take it off for daily driving.
-------jezreel

he's not installing it into the car.. he is putting it in the engine compartment.. either way.. i still would just get an electric..

Yes I'm mounting it in the engine bay. I want to use to to help me adjust my idle fuel pressure and compare it with the electric one as far as accuracy. I got it real cheap. I thought it would come with everything I needed except for the fuel rail adapter but it's just the gauge, nothing else.

actually autometer sells kits so that you can mount the fuel gauge in the cabin. its sort of an adaptor isolator, mounts on the fire wall before it goes into the cabin. I think it works like a diaphram.