Davis Unified Ignition (D.U.I.) GM ZZ-Crate Engine Street/Strip Distributors are now available for the popular GM high performance crate engines. These distributors are designed for the ZZ4(350), ZZ454, ZZ502 and Fast Burn 385. A special timing curve and a melodized gear sets these distributors apart from the standard street/strip DUI distributor. An advance weight and spring assembly is tuned to provide optimal performance specifically for the crate engines, providing instant throttle response and maximum performance throughout the RPM range without any pre-detonation. No add-on spark box is necessary as the coil and module will fire a massive .055? plug gap. Each distributor unit is polished and lubed so that all mechanical parts perform super smooth for lasting reliability and performance.