One of the best performance mods that you can do to any RWD car is to upgrade the final drive with lower gears. From the factory, cars come with gearing that is intended to provide a balance between performance and economy. Who wants economy?!
Going with a lower gear ratio (numerically higher) provides increased torque multiplication across the entire RPM range and pulls harder in every gear. This means passing on the freeway is easier, better times at the track and over all more fun drive.
Final drives do not require a tune to get the performance benefits.
Please note that these units are used, not new.
3.73 is a nice upgrade if you’re still concerned about MPGs, but want a little more performance.