I just want to state first that I am not a current member of this series, I would just like to clarify some comments about the 924s. I have the GT flares on my car and that is one of the things that kept me from joining the series when my car was built. In my opinion the 924s is an ugly car no style. Mine was just the right price a the right time.
My 1st comment is that this is not a cheap and easy modification to have made to your car. It's not as easy as just cutting the fender and slapping the flares on. There is alot of sheet metal work to be done. The weight savings is negligable. only about 1-2" of the inner and outer fender are cut off. Then material has to be welded in to close the gaps that you have now made in the fender. Even more sheet metal is added if you want to have a closed inner fender that touches the flare.
2nd, a 924s is a lighter chassis in the first place
3rd, how can you say its not "factory" have you ever heard of the 924 carrera GT. That's where these parts can from. Oh and by the way that's also where the concept of the 944 came from (flared fenders) I do agree that if they are not installed correctly they look terrible, but if they are done right they look like they should be on a race car.
Sorry, I'm just trying to squash the conception before it starts that there is an advantage and give you all some input from someone that has experience doing it.
I do agree that it should be allowed in your rules. It's a personal choice not a performance choice. If Nationals was a different weekend next year I would have put a car together for next season and may still do it for some fun during the year.