This harness offers Mil-Spec Teflon coated wire. Standard wall ethylene-tetrafluoroehtylene (ETFE) insulation ( also known as Tefzel ) designed for aerospace applications where weight, dimensional tolerance, and mechanical durability are required. This wire exhibits high chemical and radiation resistance. using standard factory wire colors with a maximum heat rating of 200°C . The Teflon coated wire is loomed with The highest quality Raychem DR-25 heat shrink covering, and adhesive lined wire junctions to keep moisture out. Each connector is crimped with pneumatic heads to ensure an OEM crimp every time, then tagged with a yellow identification label for easy installation. All heavy interference circuits are protected and grounded with proper wire covering. Our Mil-Spec harnesses are 100% quality tested pin to pin, and resistance checked to ensure no voltage fluctuations. These are the best harnesses money can buy. NO CORE is necessary when buying a harness from us! This harness follows an OEM style configuration meaning that you'll still need a interior ECU adapter for your chassis - see the K-Series ECU Adapter link and add-option below! Rywire also offers a Firewall mounted Mil-Spec connector that will allow easy engine removal for quick engine changes and customization. It can be added along with the Mil-spec Firewall Plate for a show-quality setup.