Well,
I can tell you what I've done to mine and how I liked it. I've got a 99 Silv 4.8L Ext Cab. The engine responded GREAT to the MAC intake (looks just like the KN FIPK but was under $200). I was very happy with the mod....it added responsiveness and a great growl when I punch it.
Today I had Flow 40 series 1in, 2out put on running straight out the back. I'm still undecided. It didn't seem to help or hurt performance. The sound is just a little louder than I was looking for, but it does sound awesome when punched, and quiet at cruise, but just too loud during normal acceleration. Maybe I'll get used to it...or maybe I'll put in the Magnaflow.
My next mod is the programmer. I'd take pics of the above, but you'll have to buy me a digital camera first!
