guinnepig

Anyone got a clue? I just bought a 2008 GT. When I left the car lot everyone was passing me and I had some traffic backed up. The car has had some noticeable upgrades but this one wasn't. My speedometer is about 15 mph off. When my wife in front of me was traveling 60, my speedometer showed 75. What is going on?

Lem-06

I would assume you might have 4.1 gears installed. And was tuned to fix that however they dropped the tune when they sold it.

munch

recalibrating the speedo should fix that problem more than likely a gear install reset to stock

Nuke

Agree with the above. Any mod that changes the speedometer accuracy (tire size, gears...) requires a hand-held tuner to adjust the settings for the gears or the tire revs/mile. Gear changes are a fairly common mod.

BUT.... if you DO have 4.10's and you intend to drive much, if any, highway, then I'd replace them with 3.55's or (gasp) 3.31's.

guinnepig

Thanks for the info. How can I get it tuned, the dealer? Can I do that myself with a tuner, where do I get it?

Nuke

Contact Brenspeed or AM and explain that you bought the car used and aren't sure if there's an aftermarket tune or not. Normally on a non-tuned car, you simply order the tuner with new tunes. But if you no longer have the factory tune, it makes matters a little more difficult. The tech support guys can tell you what you need to do.

The tuner with custom tunes isn't cheap but well worth the money.