MMR spark plug tap for all 93-2010 2v/4v SOHC/DOHC - 2007-2014 GT500 & 2011-2022 5.0 / 5.2 TiVCT Cleans and chases factory spark plug threads for smooth spark plug installation, cuts through carbon deposits and repairs damaged treads. Perfect for rebuilding those cylinder heads. When cylinder heads are removed simply thread in from combustion chamber side. For use while heads are on vehicle use a tap extension. (does not fit 2005-2010 Mustang GT)