Is it the fuse box with the 3 empty connectors ?

 

That's where I powered my gauges from. One spade is constant power, one is switched power (the one you want to use, far right IIRC), and one is switched power (only when the headlights/parking lights are on).

 

Far right is used for the water pump for my after-cooler should I just tap it?

 

Good info, thank you for this. It is an easy location to pull IG power for the gauge and also switched power for the auto-dimming function that several new gauges have for when your headlights are on.

And you would probably be OK tapping into the line that goes to the water pump for your aftercooler. If I remember correctly, that wire runs to the relay for the water pump, and doesn't actually power the water pump itself. The water pump pulls power from the air pump assembly; the wire from the fuse box only activates the relay, and therefore shouldn't be pulling many amps so you have plenty to spare for the gauge.