Subaru WRX STI 2004, Spark Plug Wire Set by Karlyn STI®. STI. The purpose of good wire insulation is to protect the cable from voltage leaks. The single most important factor for rating insulation performance is the type of material used and not the diameter of the wire.
- Spiral Core
- Stainless Steel Magnetic Conductive Winding
- Improves Gas Mileage and Engine Performance
- Superior Voltage Protection
- Includes Specially Designed Durable Boots
- Corrosion-Resistant / Oversized Clip-Lock Terminals
- Limited Lifetime Warranty