The KB is a phenomenal blower and you will have tons of enjoyment driving your car if you install one. That's all I can say honestly b/c since I put one on I have been on top of the world in daily driving situations. I can't say much for the track b/c I haven't ran it on one yet but I'm sure it will go low 13's easy and possibly lower on good race gas and high timing.
I'm taking it off in a week and I have to say that I'm gonna miss it a lot and contemplating getting rid of it and possibly keeping it on the shelf in case I get another 5.0. Why am I taking it off you may ask?
I'm going turbo for the first time in a Stang and I'm really looking forward to the project. I was kinda twisted into getting the KB just like I am with the turbo kit. I hear a lot and I wonder just like you are now, so no better way to find out unless you try it for yourself.
My opinion of the KB is a "10" (1-10) and I'm glad to have had one in my car b/c it has been and still is until next week "TONS OF TORQUE & FUN, FOR REAL!!!

My $.02