As above, a water one probably wont be any good if you are measuring pre-intercooler as you could see well over 100 degrees which obviously you cant with water unless its a guage intended for a very pressurised system, most car gauges stop by about 120-140 or so that ive seen and you could easily see more than that on the ragged edges of the compressor map (where most t34 cossies are ran hence the rs500 coolers being so popular, lol)