I had Isspro guages when I bought the Edge J/A so basically I'm running two sets of guages now. In comparison, fuel pressure is dead on, boost is 1 psi off, can't compare trans temp because senders are in different locations. Only running the Edge for EGT right now but it seems pretty close to what the Isspro guage was. The Isspro EGT guage was faster reacting. Engine temp seems pretty close to OEM dash guage but a lot easier to read on J/A. RPM is dead on. Not sure about engine oil pressure because I don't have anything to compare it to but it runs 20 to 80 psi depending on temp and RPM.
Overall, I would say the J/A is very accurate.