All we really do around here is index race. The only problem is getting your car to run the number in the first place. I have a buddy with a car that will run 6.16 and he spent all year and $26,000 (rebuilt the motor twice and changed the converter 9 times) trying to get it to run 6.0. If he would have run the 6.50 class (we have one of those here) he would have had an easy (and inexpensive) year. But noooo, you know drag racers, they always want to go faster. 6.0 and 7.0 are popular. 6.0 takes a lot of power and eats parts. 7.0 is cheaper and easier to make hook up. Index racing is great and you are still set up for bracket racing if you want to do that.