All guages work with no problems. The only issue we are having is a low water pressure problem but I think there is just a kink in the gauge line somewhere (grey hose). It sets the alarm off at low throttle. Water pressure is as follows, idle 1-3psi according to mercury acceptable. Low throttle where the alarm happens 3-4psi. 1/2 throttle 4-7 psi acceptable range 4-9. We haven't gotten her WOT due to break in. I think there is just a small kink or pinch somewhere thats causing it to have funny readings. Once we get on plane and moving at about 3600rpms its fine when I back off down around 10mph 2,000-2500 rpms the alarm cuts on and backs the power down (not a tahoe issue this is a mercury issue).