SKUNK2 COMPOSITE FUEL RAIL HONDA K-SERIES K20ZSkunk2's cutting edge Composite Fuel Rail for the '06 '11 Civic Si is here. Skunk2's Composite Fuel Rails are made using a proprietary carbon impregnated, aerospace thermo polymer compositea material that's 33 percent lighter, 60 percent stronger, and operates up to 100 degrees F cooler when compared to aluminum and insulates fuel from both radiant and conductive heat transfer underneath the hood, resulting in increased horsepower and torque.