The biggest difference between McIlroy’s custom set, and the stock P730s, is the design of the grooves on the iron faces. While the P730s were constructed with 14 MX-9 grooves on their milled faces, McIlroy’s versions utilize the higher-spinning, 16-groove layout of the TW2 grooves. Additionally, McIlroy’s 7- and 8-irons have thinner toplines, are 1 degree stronger in loft, and they’re 1/4 inch longer than the original P730 builds.