Ultra 40 Wire Set 8.5mm GM LS/LT 9.75 Black

The Ultra 40 Wire Set 8.5mm GM LS/LT 9.75 Black is a premium spark plug wire kit engineered for General Motors LS and LT series engine platforms. Designed for enthusiasts and professional builders who demand reliable ignition performance, this wire set replaces OEM spark plug wires with components built to handle high-RPM applications and modern engine management systems. Whether you're upgrading a classic LS-powered hot rod or fine-tuning a modern LT swap, this kit delivers the consistent spark delivery your engine requires.

The Ultra 40 features an 8.5mm spiral core construction, a proven design that reduces electromagnetic interference while maintaining superior spark integrity across the entire RPM band. Each wire terminates in a coil-style connector on the distributor or coil pack end and straight plug boots that seat securely onto spark plugs without twisting or binding. The black jacket provides UV and heat resistance, protecting the core from engine bay degradation and ensuring longevity in high-temperature environments. This spiral core technology is particularly effective in LS/LT engines, which benefit from the noise suppression and signal clarity this design delivers.

This wire set is ideal for LS and LT engine swaps, street performance builds, and restoration projects where OEM or original-style ignition systems are being retained or upgraded. Installation is straightforward—remove old wires, route new ones away from hot surfaces and moving components, and connect to your existing coil pack or distributor setup. The 9.75-inch overall specification accommodates standard LS/LT engine bay layouts, though fitment may vary depending on your specific fuel injection setup, accessory drive configuration, and custom intake manifolds. Verify wire routing clearance before finalizing installation to ensure no contact with exhaust manifolds or radiator hoses.