The Nissan has only a single 3 inch duct per side, and they are located in the radiator opening. I have room to run the hose through an existing internal opening, so I don't have to cut anything. My car may be heavy, but it has big vented discs so I can get by with that little brake air. But it's marginal and I'm trying to decide how to run a second duct.

A problem I have with the rule that you cited is that on my car, it is easiest to have the airdam as a "chin" spoiler (i.e., a small strip - 3" tall - of plastic) bolted to the bottom of the stock valance. That leaves me without any real room to install an inlet into the spoiler. I'd like to install a 5x7" duct into the valance, but if I do that I'd have to eliminate the spoiler altogether.

So my options are:
1) chin spoiler and no more ducting
2) a bigger airdam (large enough for a duct) and cut a 3" hole in the valance, or
3) remove the spoiler and install the duct in the valance.

A fourth option, using the chin spoiler and a duct in the valance, wouldn't really allow me any advantages over the other three options. But it's illegal as the rule is now written.

I had a long discussion with Jeremy Thoennes about this, but I couldn't even get him to even understand what I wanted to do (I didn't think it was that hard). Anyway, I never could get any consideration of a change. But then I never sent in a formal request, either.