There are many important reasons to use ARP head stud kits for your 1.6 or 1.8 Mazda Miata, including the elimination of lifting your head, as well as protecting the threads in your engine block. Every ARP head stud kit exceeds the most stringent aerospace specifications. All kits come complete with hardened parallel-ground washers and aerospace quality nuts. The studs are manufactured from 8740 chrome moly steel, heat-treated in-house to 190,000 psi tensile strength, and precision J-form threads rolled after heat-treat to create a fastener that has threads 1000% stronger than others.