I'd call Ridetech since you are running a stock subframe. Your spring rates are a big factor here as well. I had a bar on the rear of my car when I had the low spring rate(175) and it worked well. I found my car to work better with a 275 rear spring rate and no bar though. Since you have no tire up front
you are going to need one to counter the lack of front traction as Dave said.
Personally, I'd get more tire on the front before you worry to much about a rear bar. Otherwise, you will be starting over to some degree.
I have a Prodigy bar basically.