From another thread in the Tires section, I would agree that "C1" seems to be the key identifier. Are you going with PS2's all around or just the front? I can't seem to find out if Pilot Sports are available in my (stock) size - I know Tire Rack doesn't have them. I may be going with PS2's as well.
I'm getting a full set, but I understand that the size used for the fronts are built in two different versions for the Viper and for Mercedes. I'm looking for some direction as to where exactly to look on the sidewall for the "C1" when I pick up the tires. I use the philosophy, "Trust, but verify."
To my knowledge, at least the rear size original Pilot Sports are no longer available except as residual stock here and there. The Pilot Sport 2 version is the current model, and what you really should get.
I have been dealing with the same tire place for years before I bought the Viper, and they have always treated me very well. Although I'm inclined to support the Viper vendor community, there is the other side of me that says "support your local merchant whenever possible/practical."