yep you have to start off in novice for up to a year, so regardless youll still have to figure out how to class your car:
eg. your open class is street mod: SM
your novice class is novice street mod: NSM
basically your PAX will still be applied but you will be only competing amongst the novices (PAX is a method of adjusting your raw times to level the playing field, in order to compare slower and faster cars)