I'm in favor of doing away with the VIN rule. I would love the opportunity to cheaply upvert (wd?) my ITC ride into an ITB car... :blink: I'm already out qualifying several of those cars on the grid :eclipsee_steering: only to be passed later in the race.
As for adding a sunroof, only to deleat it later... that's wasted money and effort. If the car makes weight, does it matter? In fact, if the high centered additional weight is the concern, then a stipulation to add weight up high could be added.
Nontheless, going and racing ITB would only add about $1500 expense to my already built car... vs building a new one for $7000 or so.