When you register for PE1 you'll notice a note at the top of the page breaking out 10 indexed "Super Classes." If your goal is more competition and fewer classes, register for the appropriate one.
With PE1 also being a Great Lakes divisional this complicates things a bit, as if you are running for Divisional points you'll need to register in your regular class. If you don't care about divisional points, you can register in an indexed class and it doesn't matter. If you plan to run for Cincy points in an indexed class but also divisional points in your class, I guess you need to decide which is more important for this single event. I suspect the number of people this actually applies to will be minimal.
Both the indexed classes and the regular rulebook classes will be offered in an attempt to not force the indexed classes on people, so we will have way. way, way too many classes to deal with. But the hope is that the 10 Super Classes catch on and effectively obsolete all of the smaller classes that only have one or two people ever registered.
I suggest getting in an index and running there all the time unless you have a regular class that is normally well attended. Competition makes you better. Competition is FUN!
SO - Street Open - all Street class cars and will be PAX based.
SRO - Street Race Open - all Street R cars and will be PAX based.
STO - Street Touring Open - all ST cars and will be PAX based.
SPO - Street Prepared Open - all Street Prepared cars and will be PAX based.
SMO - Street Modified Open - all Street Modified cars and will be PAX based.
PO - Prepared Open - all Prepared cars and will be PAX based.
MO - Modified Open - all Modified cars and will be PAX based.
T - Tire Index - all non-Street cars on street tires and will be PAX based. In addition to the PAX of each car there will be a blanket PAX added to the class like in 2013.
X - Pro Index class.
N - Novice - for all people participating in their 1-3 autocross event. PAX based