G35, FX35 & M35 1/2" Copper Iso Thermal plenum spacer (with all Iso Thermal components, Aramid Gasket and the Polarized Copper TB heater) This premium stealth modification adds 12HP-14HP and reduces the effect of power robbing heat soak. This plenum spacer can be used for maximum performance enhancement. It also adds a substantially deeper growl under the hood. Use the copper if it ever snows in your area.