I am getting ready to add fuel pressure gauges to a pair of 2000 500 EFI's and wanted to wanted to get input or advice on whether going with electrical or mechanical gauges would be better. Any advice would be appreciated!

Good add on to have! I struggled with 2 bad pump last summer on same model year engine!

If you're going to run it to the dash, electric. I am currently building 2 EFI systems. I have a mechanical gauge at the regulator and will have electric at the dash. I then can reference that they are the same.

Regulator is kinda under the engine so where do you put it? Remotly somewhere else readable like 2-3 foot away?

I guess it depends on what fuel pressure you are looking to read but ours is near the fuel filter...