30/9-15R on my car and I love them. they are supposed to be at least .05 better than a bias ply. Also know guys that have back to backed them with Goodyear and the Hoosiers seem to be the fastest tire.
Give Hoosier a call 1-574-784-3152. I can't remember the guys name but just ask for drag slick help. They are very helpful and can set you in the right direction. I have run both compounds but can't say if one was better than the other.
I had 30x9R's with C07 compound on my car with the big-block in it. They are about .05-.10 faster than bias. The only thing I didn't like is they would break loose easier on a marginal track, and once they spun they wouldn't recover. For that reason, I didn't like them for bracket racing.
We don't recommend them for bracket racing either. The difference in the tires is the C06 is a lighter tire by about 2Lb.'s I can tell you off my truck at the divisionals and national events I sell 80% C06 tires.