Porsche CP-Carrillo connecting rods are fully machined from a proprietary 4330m alloy forging for strength and durability. Rods are available with 2 types of bolts: The standard WMC-H7 (H11) bolt with a UTS of 220ksi and our upgraded CARR-S7 (MP35N) bolt with a UTS of 285ksi. The CARR upgraded bolt is a good choice if planning on revving the engine higher than 8500rpm. All our bolts are manufactured with asymmetrical threads, each thread has a slightly different design than the previous giving the bolts an evenly distributed thread engagement. This helps increasing the clamp load and fatigue life of the fastener. These Connecting Rods Set for Porsche 997 Cup 130mm Long 23mm Pins with CARR Bolts.