Exhaust Jacket Kit (4-6 Cylinder Vehicles) by Thermo-Tec The new quick-wrap high-velocity Exhaust Jackets are an innovative way to insulate and block radiant heat. The jackets cover the tubes vertically allowing for a consistent fit. The fit allows the exhaust system to expand as it comes up to operating temperatures without restrictions and provides air space for added insulation. The part number for this item is 11246