I have decided that when the time comes to get my twin screw it is going to be either the KB or the Whipple. I can easily see how the OP came to this point. Their both around the same price range and similar in the performance range also. The two factors which, in my mind are the different deciding factors are; even though the KB may be harder to install, There are certain advantages to the way they set up the CAI which I really like. The other factor that is swaying me towards the Whipple is that 10 rib dedicated belt drive Steeda makes. That is the way we used to do it when we were kids. and you can always custom fab a CAI for the Whipple.
I'm thinking Whipple would be my choice, I've never run either one so I can't really tell you which one is better, just sharing my thought process on this subject 'cause it is a question that I have thought about for my own car and researched pretty thouroughly.