I actually talked to Kooks about that today as we were going over a few other things as well. I also discussed the installation with Mike at 5Star tuning. What I have ben told is that the installation is very similar for both Kooks and SW. Mike said the Kooks do have a little more room around the alternator and according to him that does help some. Also, although they haven't done so in the past, the one catback system they currently offer for the Raptor that has been only for the Screw is now going to be made available for the Scab as well. I have been talking to them about offering another catback version since their current offering is a true dual exiting under the rear bumper, but they have not finalized what they are doing with that just yet.
Just to throw this out there, I am beginning a sale on Kooks headers with custom tuning from 5Star next week for anyone interested.