how much work is done to your car?

A/F guage is stupid if you dont get a wideband O2 sensor to go with it.... if you use the stock sensor, you just have a light show in your car.

Oil Pressure isnt a bad idea, since we only have lights in our cars, it can help keep an eye on your oil and if you are burning or have a leak, it is an especially good idea

I dont see a need for watertemp but im sure somebody else will argue that its a good one to have...