WTF did you just ask??? no you dont NEED a fuel pressure gauge but its nice to have. IMO an AF gauge, a fuel pressure gauge and a nitrous pressure gauge are all some nice fluff if you can get em mounted aesthetically....thats the key though, aesthetically mounted shit!!
id do the two pod a pillar for the nitrous and fuel pressure and then use the AF for the steering column (an old VEC1 LED display if you got one)
I finally have the vacuum and fuel pressure gauge mounted on the piller. I have the A/f logger hooked up permenantly and can log at any time. An a/f gauge is too hard to read, it needs to be in the form of a logger to make it practical.
I also have the the fuel pressure and vaccum hooked up to the logger. I do like the ability to watch the fuel pressure in the car. The reason for the vacuum gauge is for tuning the VEC. As an example I have I minor hesitation at 2000 rpm and at light throttle. The only way to add/subtract fuel at that event is to know what the vacuum is.