A chip will most likely decrease your MPG slightly, but wont by itself lessen your engine reliability. For a 4 cyl, I would look at other intake/exhaust mods way before the chip. The ATX has much higher driveline losses than an MTX so performance (if we can call it that
)is limited at best. Switch to 100% synth tranny fluid and check the Zetec forum for the best mods. (You can to a lot...) With the market price of contours these days, if you really hate the ATX, sell it and find a used MTX tour for cheap.
