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I also heard they help you get better gas mileage. Is this true?



It's possible, but having a chip means having to put in Premium gas. To notice any effect anyways. They're tuned to take advantage of Premium.

So, if you don't do that already, even if your gas mileage goes up, you'll still be paying ~20 cents a gallon more, so it'll cost you in the long run.

2003 Mazda6s 3.0L MTX Webpage 2004 Mazda3s 2.3L ATX