When you start putting on the sticky rubber, stock axles will fail even at 200hp. So the folks over at the Driveshaft Shop started with the direct-fit billet chromoly outer CV from their Subaru axles, 300M center bars made from the material out of Sweden, which is by far some of the best material used to date. They then went on to make the inner splines out of the same material, and used a 108mm Porsche-style inner CV with upgraded chromoly internals to top it off. This set of axles was designed with punishment in mind so don't be easy on them. These are sold as each, so add 2 if doing both sides.