In order to run for points and a trophy, IMHO the main reason for attending, you have to run PS1 or PS2 tires.
CT would need to clear up the rules on the class Matrix on the Toyo's. As I read those rule you may need a roll bar to run shaved race type tires. They rules state to run a "cup" tire then a roll bar is required. I have a street car (GTS) and no roll bar. I know the place Dan speaks of, I told him about it

and Sled had told me. OTR is running the following Wednesday so if I just wanted to track my car and save some money I'd probably do that.
But for me, Viperdays is different. It's a chance for some real bragging rights and as close to "true" competition as I'll get. A couple of years ago, Doug Dye and I went at it in each session. He'd lay down a fast lap, then me, then him...back and forth. I got beat by a small amount by that old fart.
The caliber of support if very good, in fact excellent, as compared to other HPDE track events. The fell of the weekend is very "race like". I've run willow a few times, I'd love to go...I just don't think a >$3000 weekend is in the cards.