You can measure the final drive ratio by: 1 Jacking the car up and measuring the ratio of prop shaft turns to drive shaft turns, details available on request, or 2 Measuring the road speed (eg with GPS) at a known engine speed at a known gearbox ratio with known tyre circumference, ditto. ... Which gearbox do you have? ... Road, track or both? What are your current thoughts about: The engine speed and noise when cruising? The usefulness of first gear?Jonathan