Coil pack upgrades (as in, an upgrade beyond the usual drop in splitfires) are pointless unless you're running a serious setup with which the standard coil type can't keep up. You don't so much net gains with better coils, you just retrieve lost power through poor quality or worn ignition components. Simply put, unless you're running a drag or drift car with 1000hp, or your coils are worn, stick with what you have. Buy the new set and onsell your four to someone else?