I have an '87 325ES - the tach is consistently (and smoothly) inaccurate. It reads only slight low at idle, but at LEAST 1k RPM low at redline (ie: rev limiter kicks in at ~3600 on the tach - eta engine, remember). VDO gauge cluster (I've heard there is another brand). Any ideas? adjustments? Help me out if possible. I'm interested in chipping the car sometime down the road, and a working tach would be nice with the increased red line. Thanks.