You do not have to run fuel inside the cab with a mechanical gauge. Autometer sells an isolater kit. With this kit, fuel only goes up to the isolater, which you mount under the hood. Between the isolater and the gauge is anti-freeze. It takes a little time to get it set-up properly. You have to make sure you do not have any air in the line. Once you are finished, it works great and is very accurate. I had one on my Turbo Buick. You will probably pay just as much, if not more, for a complete mechanical set-up with the isolater. You will need 2 braided fuel lines and a couple of fittings along with the gauge and isolater. I would think that the new electric fuel pressure gauges are very accurate compared to the mechanical ones. Overall they are probably even a little cheaper. When I wanted a fuel pressure gauge for my Buick (that was mounted inside the car), I had no choice. The only thing available that was accurate was an Autometer mechanical gauge w/ isolater. At that time, Autometer just came out with the isolater for fuel injected cars (over 20 PSI). Now you have more choices available. Another thing with the mechanical gauge, that is a pain, is runing the braided line to it. That is something else worth considering when making your purchase. Bye the way, I have the Autometer Pro-Comp electric boost gauge (full sweep) in my truck and it is very accurate. Hope this helps you a little