IVR

Agree with Dana. Yes, some of the cheaper electronic IVRs are "lazy", but they do work. If you want instantaneous readings, go with the RTE IVR. I'd never put together a cluster with the mechanical regulator anymore, not worth risking increasingly rarer original or increasingly more expensive reproduction clusters. They worked in their day, but the first time you have to tear your dash apart again or replace a gauge, you'll be cussing yourself out for not doing it the first time.