I have a 1997 Pontiac Firebird 3.8L M5 with a Y87 rearend that I installed. Stock gearing ratio was 3.23, now its 3.42's. How do I go about recalibrating the speedometer so that it's correct? What are my options? I read that you can use a Hpertech Pro tuner but I cannot find one, not even on their website. I also found PCMforless which charges $150.00 to flash the pcm. Any other options or does anyone know where I can find a hptuner to correct my speedometer?

 

If you plan on doing some other modding, go the PCMforLess route as they can factor all that in when they tune a new PCM.

I did that when I put on headers, LSD & new rear gears. Worked like a charm.

 

Yes, you need to re-program your PCM. A decent speed shop, that tunes these cars could probably do if for you more cheaply than buying a Hypertech. You can also have it calibrated for non-stock sized tires.