ProFire:

Performance Coils for 5 HP & 3 HP Briggs & Stratton® engines::

Finally, a high performance ignition coil for the 5 HP and 3 HP Briggs & Stratton engines. This coil is absolutely essential for the serious Go-Kart or Jr. Dragster racer. The Briggs coil has a resistance of 4400 Ohms and features the most impressive performance data. This coil will deliver just the kind of spark you need when building a race winning, high performance machine. The NOLOGY ignition coil for Briggs & Stratton is available for the 5.75" and 6.75" diameter flywheels. Coil voltage and current output is much higher than stock, and timing retard is 30% less.

If you're not using ProFire, you're not going as fast as you could be.