As someone said, the hook was added to the PS209/X-9 starting in the 2003 model year. Some owners (me included) got the hull hooked on their earlier models (mine a 2001). My complaint was porposing at speeds generally faster than 35mph and a less than ideal wake for slalom at recreational speeds (28-32). The hook cured the porposing and helped the wake quite a lot. The hook is a small tapered "ramp" along the bottom at the very rear of the hull. It is only between the left and right most-inboard chines. It drops down 1/4 inch at the back and tapers to nothing as you go 1 inch forward. What many may not realize is that all the early evo boats lacked the hook...190's and 197s. When the Pro Tour boats came out (in 2002?), they DID have the hull hook, but the civilian models did not. From what I understand, porposing was not an issue on the 190/197 but rather the hook made the slalom wake even better than it was without it. In 2003 all 190/197/209 boats had the hull hook incorporated into the hull molds.
2001 ProStar 209, Red/Gray/White