FIPK comes with a conical airfilter and a somewhat "cai" system. It has a little plastic plate behind the filter that is supposed to shield the intake from warm engine bay air.
I sell them, not very often but customers report responsive throttle, better gas mileage and a growling intake sound (some like this) but they also say they didn't notice much more power. With this kit you aren't MAKING additional horsepower, you are freeing up horsepower that you already have but is locked up in a restricted intake and exhaust system. Your not really making more power from your engine, because it's already there yet its not readily available because your engine cant get every last cubic inch of air it really wants. Perfect compliment to a highflow intake though, is a high flow exhaust. You will notice a big gain in gas mileage.
My dad's 2002 Grand Cherokee 4.7 HO (stock) would do a 550 km trip on about a tank of gas, with his Dynomax Ultra Flo Welded kit, and his FIPK he can do the same trip and have almost half a tank of gas left afterwards. Forgive me i dont do MPG numbers or KmPG (lol) i just go by distance because its easier to picture on a rough scale.
Anyhow, don't bother getting a shop to install your FIPK, as a 10 year old could install one if he can tell the difference in size between several sensor holes and can turn a screw driver. Save yourself the $100 or so. For your flowmaster question, you'll have to get someone else to answer that, ive never dealt with flowmaster although i heard an 80 Series on a V6 Bonneville SSEi and it sounded like a Civic letting off the gas at 15,000 rpm (eww).
