This will be a BIG FLAME, but here goes
The problem is not the chassis'. The problem with stock is the "same" ole guys keep winning and are not moving on. Modified may not be the answer, but 19 turn sure is a good alternative. Keep the factory modified guys out of 19 turn and let the fast stock guys move on. If modified is the answer their needs be an open modified class with a 10 turn motor limit and a Factory Modified class that is unlimited. These type of things will get the current fast stock guys to move on and make way for new "fast stock" guys.
If you win a ROAR stock event you should be forced out of stock. If you podium three times (2nd or 3rd) you should be forced out.
I also think brushless should be looked at a little harder. Much cheaper in the long run. Easy to tech with a meter. But, 13.5 is not the answer. We have proven it 100 times that a 13.5 is and can be faster than a stocker. I did some testing with a 17.5 and ran the same lap times as I did in stock. Brushless just takes a "BIG" gear and they can be faster. Brad Johnson just won stock at the IIC and I guarantee you he would have went a "lot" faster with a 13.5.
This post was a little off topic, but I truly believe it is something ROAR needs to consider for onroad stock racing......