As long as you're not trying one of those "hydrogen generator" kits, if so we're finished here.
Anyway, the truck guys aren't really that knowledgable on your engine. The intake is cold-air as mentioned, and the exhaust is not that restrictive. You could go to a 4" exhaust, throw on a larger CFM filter system, and I doubt you'll pick up 5hp. The turbo and IP aren't going to put any more air and fuel in the system, so you haven't changed anything significant.
Now if you want to add power, it can be done, at a cost. And if you add a larger turbo and larger elements to the IP, then an aftercooler, you'll need a larger intake and exhaust.
http://www.youtube.com/watch?v=TVXLXuUYjvs&feature=related
http://kuvablogi.com/blog/6520/16/