I searched this forum and didn't come up with any answers, so I am soliciting your advise. My speedometer and tach are not indicating properly. I have an engine analyzer that reads actual data and the speed and RPM shown on the analyzer indicate properly (speed verified against GPS). Speed indicated is approximatley 15 to 20% higher than actual. RPM's are 400 to 600 higher than actual. I would have thought both would indicate the same but appearantly not. The odometer tracks accurately as well. Only changes made were an after market radio and I replaced the turn signal switch assembly. Everything else seems to be working properly. Any thoughts? Thanks in advance.