Interior modifications

What modifications are allowed to things like the dash and other interior panels in intermediate pro class? Advanced? I've read the rule book over and over and all I can find is stuff in the spl testing section saying please refer to modified spl rules for for mic placement and vehicle interior modifications permitted. Along with seeing things such as seats must be in the factory locations and function as originally intended.

I know this hasn't been the case in all intermiate cars recently. Is there an addendum to the rules that explains this or can someone let me know what is and isn't allowed before I start my build. Ralph your input would be appreciated on this matter.

I'll tell you what we've seen...the most radical dash build cars that were in Intermediate are both in Advanced now. It was by their own choice though. Extending seat rails or changing seat mounting points should fly as long as it's still as strong as factory or stronger IMO.
USACi's book is vague there.

Pretty much, you can do what you want. As long as it still functions as a normal car. I know the you can build a custom dash and extend seat rails because we did this in Lou's Lexus.

Thanks, I guess that's what I needed to know. Time to get building.