Derek texted me last night about this. I can't find anything in the wdra rulebook about it. They told him 6.99 or faster 1/8th. Here is all I could find in the book.
Not sure if it’s still that way but a track can require it. My son Matt was required to put one on years ago. His car ran 6.54 and Greg told him to put one on, so he did. Honestly it a great rule and my save your car someday.
