Autolite’s 3910 (left) is an excellent cold spark plug for boosted, high-horsepower street/strip engine’s like T-top Coupe’s. However, the all-new 3910X plugs (right) are super cold and more in tune with setups that make upwards of 1,000 hp. “The 3910X sticks farther into the combustion chamber and raises the compression ratio slightly, while maintaining a cold heat range,” according to Autolite’s Jay Buckley. The new plugs, inspired by NASCAR race engines that were having issues with burning up their spark plugs’ side wires during 500-mile races, have eight individual firing edges, which don’t require as much voltage as standard plugs. The efficiency results in increased dwell time and produces a bigger flame kernel for improved combustion.