most OEM gauges are crap.. even the speedos...

hell, the idiot lights don't come on till whatever is critical mass... i had lost my oil drain plug as i was driving, aftermarket oil PSI dropped to 1-2psi, and the oil light hadn't come on yet... if the gauges reflect that, in any way shape or form, i'll go aftermarket, even the cheap ass sunpro stuff...

one of the first things i bought for my GTR was a Autometer boost psi, oil psi, and water temp gauges, same as the OEM gauges that were in the center console, but i don't trust the OEM for shit... hell, i was hitting 20psi and the OEM boost gauge was reading like 12ish....

on RB26's, the oil psi sending unit is JUNK (same as Z32 IIRC), even ordering a new one sometimes doesn't solve the problem, it'll read 5psi (in standard measure), when in actuality, it'll be around 20-25psi...

me? about the only OEM gauges i trust are the speedo, and tach, and even those can be off, hell, i think most auto manufacturers have a 5% margin of error in the speedo calibrations