theres still good things you can add to a stock car-
oil psi - the stock oil psi gauge is UP at 8lbs, dead at 7. its a 'switch' gauge. (gay)
trans temp - a MUST for auto guys.
water temp - the stock water temp isnt quite that bad, but its not anywhere near exact.
fuel pressure - a nice thing to know as there is no stock gauge.
and definitely get all electric. mechanical gauges arent any more accurate and are far more hazardous.