While I agree the numbers originally quoted look questionable, I found this on the K&N website:
"Our systems are built for horsepower. In fact on the 2003 Ford Mustang SVT® we get an impressive 30 horsepower"
So while we all might initially question a quoted "30 hp gain" for our beloved IS-F's, or would be much more willing to accept a more normal 8-12 hp gain, we usually see for replacement air filters or CAI(cold air induction) units for other cars, I am not so sure that K&N could NOT come up with something interesting for our cars. Though it is interesting to note that a previous attempt to build a CAI system for our IS-F's by another noted CAI builder only yielded a 1 hp gain???
So at this point all we can do is to wait for K&N to respond to our numerous inquiries or to reveal their product in some other way via their own marketing department. And in the mean time we can all hope that what we've read and see here is indeed a product that will perform as represented and that we all can get buy, and SOON !!!!
By the way Jwain, I live in Los Angeles and would be willing to drive to YOU to see what K&N has done. I run my IS-F with both intakes open at all times but can't say that I feel any HP gains, though I do feel a slight decrease in the throttle response time so that's why I continue to run with both open all the time. So to see what K&N has installed and how they are getting what's claimed by just adding a different air filter and a smooth metal pipe in place of our plastic pipe would be most interesting to me.... OR did they really do more then we can see from the pictures?