All of the responses are correct regarding the faster rating and jib pole addition to accomadate the larger jib of the MX sails. In addition, the jib pole gives you attachment points to install a 3:1 jib luff tension adjustment. I have owned my boat for 9 years and have sailed with both the standard and MX setup. The enhanced speed downwind is pretty obvious with the larger sail area. One of the biggest benefits is the ability of the square-topped mainsail to twist off in the puffs. The boat is more forgiving and easier to handle in those annoying gusty winds. I wish there was at least one other P19 out here on eastern Long Island to race against. It's still a fast boat and I have frequently found myself out front all alone hoping I can do well on corrected time. On the positive side I'm always in clean air. Greg