has anybody used one. how were the gains. hard to instal??

about the same gains as any of them. the install on intakes is pretty simple, you just need to pull the stock airbox, MAF sensor, and intake tubing and install the new intake with the MAF inline with the intake tubing.

Let me preface this post by saying that I do not have any personal, on-hands experience w/this intake only that I had researched this one also a few years back.
I too was looking at that intake for a while, they do make it sound good and their pitch seems to make logical sense too. I was warned at the time that they are not well put together, and seeing as how they rivet one tube inside another, anything could happen. If the rivets are not tight, or loosen up over time, one could potentially be sucked into your engine.
I can also tell you that the few on the boards that I know have installed it are not raving about it, so what wsoape281 said about it is probably the case.