On my '02 Boxter, my Analog speedo reads wrong vs the RPM chart in the manual and compared to the digital readout. At 2000 RPM (IN FIFTH) I'm showing 52mph digital and 60mph on the analog. At 3000 RPM, where I should be doing approx 70mph, my analog is reading 90MPH. Any ideas on ways to correct this, short of pulling the speedo and sending it to Hollywood? This isn't a Kilometer vs MPH conversion that can be selected by the owner is it?