Yeah, once the bug hits ya, put a fork in you....you are done.
Was this a SCCA event? If so, was the guy with "slicks" in your class? He should not have been.
As far as tires go, the KDW's are a great street tire. I too would suggest you pick up a set of extra rims and get some Falken Azenis mounted on them.
And Like everyone else will tell you, there are 3 things that will make your car faster on the course:
1: Seat time
2: Seat time
3: Seat time
The more you drive, the better you get, plain and simple...Have fun, and good luck!