Being that I ran nss for so many years my take is when they legalized them for the old nmca cause Indy was the class sponsor. I ran a low deck combo with stage six heads for years with a stock crossram. When looking at the motor it seem way more correct looking but found that that combo was not legal for the class any longer.I guess a Indy bathtub and alum . 605cu. in. looked more correct(LOL). Looking at the 422 rules with 14/32 tires seems to open the doors for possable more car count from some braket cars!! Personally I prefere the 10.5 rule. It makes it more interesting to make work with a faster car. Jake