I have. It's not pretty. You give up a lot of power. Driveability suffers. If my chip (and car) hadn't spent a day under water last year, I would still be fiddling with it. The margins for gains aren't really that big, I think over a proper power tune.
Typically, a naturally aspirated flash tune already makes the car slightly more economical... sometimes manufacturers add a little too much fueling at low rpm... a good clean up pulls back fueling at idle and at low rpm and cruising rpm.
|