Hi, I realize this post is pretty old, but also noticed that no one here really was able to answer your questions about the class breakdowns. The breakdown of the triple classes doesnt have anything to do with the laydowns; most of the big laydowns are running 4 cylinders.
The triple classes were broke down so that the big triples (Triple Caracals and Triple Saberteeth motors) could be in a class of their own. The classes were designed with the future and mind, the 2007 Planet Sand Drag event. At the 2006 PS Drags, K&T dominated the twin classes with their Saberteeth motor, and the question was raised is it fair to race a 1100cc motor against 600-800 cc motors? The answer was no, so new classes were designed. Therefore, the triple class was broken down as well, and it came just in time. There will be some "big triples" in LA next week, should be interesting to watch
By the way, hope my information was helpful, and I'm not just considered a twat from over there, lol.....