Moroso 28329 Ultra 40 Spark Plug Wire Set for Harley-Davidson Softail

The Moroso Ultra 40 Spark Plug Wire Set (PN 28329) is engineered for high-performance ignition on Harley-Davidson Softail models. Trusted at the highest levels of motorsport — from dual-mag Top Fuel dragsters to NASCAR Cup Series competitors — Moroso Ultra 40 wires represent the benchmark in performance ignition wire technology.

At the core of the Ultra 40 design is an 8.65mm diameter wire featuring a precision spiral-wound conductor that delivers maximum energy transfer from coil to plug while actively suppressing electrical interference. With just 40 ohms of resistance per foot, the Ultra 40 strikes the ideal balance between signal integrity and noise suppression — significantly outperforming standard OEM-style wires.

Key Features:

• 8.65mm diameter high-performance ignition wire construction
• 40 ohms/ft resistance — optimized for maximum spark energy delivery
• Spiral-wound conductor design for superior energy transfer efficiency
• Optimized EMI (Electromagnetic Interference) and RFI (Radio Frequency Interference) suppression
• Race-proven technology used in Top Fuel, NASCAR, and other professional racing series
• Direct-fit replacement wire set designed specifically for Harley-Davidson Softail applications
• Durable, heat-resistant outer jacket built to withstand the demanding engine bay environment

Whether you're building a high-output Softail street machine or a dedicated strip bike, the Moroso Ultra 40 plug wire set delivers the reliable, low-interference ignition performance your build demands.