The accuracy between the Mech and Elec are identical according to Autometer. I like having my Mech Oil and Water gauges for the track I will always no my current water temp even while the car is sitting in the pits. Get the electric Fuel Pressure gauge it is the only way to go and is NHRA legal. You could get the A-Pillar mount and get the FP, A/F or something else in the 2-1/16", and then just mount the tach in the dash pod with two 2-5/8" gauges, H20 and Oil. The tach needs to be somewhere easy to see. Why do you want to hide the gauges?
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My Ride Check Out My Site 91GT, Holley SysteMAX II Kit-Heads 2.02" x 1.60",Full MAC exhaust 1-5/8" Long tubes, 2-1/2" O.R H-Pipe, 2 1/2" cat back, 12" K&N Filter, RNH PERFORMANCE Ram Air, Ron Davis Radiator, Full Suspension,3:73's, Welds, Best on new motor-12.60 @ 108, no traction 1.98