Engine builders understand the need for high-strength holding power and fasteners that are precision-engineered to handle the extreme stresses that high-performance diesel engines produce. The PPE Head Stud Kit exceeds industry standards required by performance engines. PPE Head Studs are precision center-less ground for accuracy. Threads rolled to Mil-S-8879 specifications for increased strength while reducing stress at the threads. Whether on the highway, off-road, strip or street, confidence comes from knowing these Head Studs exceed your needs. Highly recommended for boost levels 45 psi and higher. With an independently tested and verified tensile strength of over 231,900 psi, these Studs out-perform even the most venerable manufacturer. Kits come complete with hardened parallel washers, nuts, and specially formulated assembly grease for uniform load distribution and accurate torque readings.