I think Performance Cats first made the P19 in 1984. Supposedly, the Tornado sailors wanted a trailerable boat that was very similar so it would be easier for them to train between olympic regattas. The only thing Dennis didn't mention was that the MX upgrade also includes a "jib pole". This is a two piece aluminum extension that attaches to the front of the main crossbar and the bridle. The second piece mimics the angle of the forestay. The MX jib has a lot more sail area in the foot. I've sailed with both the old and new setup and the MX is much faster downwind. Upwind there is a lot more power but it feels more controllable with the square topped main twisting off when you crank on the downhaul in the gusts.