Audi 5-cylinder Connecting Rod Bolts (2.2, 2.3l): Pro Series Wave-LOC Rod Bolts ARP2000. For the most severe applications, in conjunction with aftermarket I-beam rods, ARP has developed the “Pro” Series Wave-Loc bolts. These ultra heavy-duty rod bolts are made from a special material designated ARP2000. It has approximately 200% the fatigue life of 8740 chrome moly steel and has a tensile strength of about 220,000 psi, and is capable of more than 12,000 lbs. clamping force. Because there are fairly wide tolerances in factory bolt holes, the bolt must be able to fit snugly and a knurl is applied. Unfortunately, these knurls cut deep into the bolt material, leaving sharp edges and enormous “stress risers” that promote failure. That’s why ARP developed the ARP Wave-Loc design that features symmetrical waves and provides an effective interference fit without creating stress risers in the bolt or the rod.