Reading Topic: 1/4 miles times
If the limiter is 6750rpm, and mazda6s2 hit 7200rpm, then the tach is "fast" by close to 500rpm. Not cool. Maybe yours is just closer.
Since the torque curve is pretty flat, it's a little tough to do in this car, but you can self-calibrate your tach with your "butt-dyno". The two distinct point in the torque curve is where it picks up at 2700rpm, and then the little peak right at 5000rpm or so. You can check the accuracy of your tach based on those two points, since they're engine related and aren't going to vary much.
For example, we know the engine picks up on the low-end at 2700rpm. We also know there's a little peak, which you should be able to feel, right at around 5000rpm. If according to your tach, those points don't occur until 3300rpm, and 5500rpm, then you know your tach is about 500rpm fast. Adjust shift points accordingly for maximum performance.
