I've not got much engine knowledge at all considering I've got 1000 posts Matt
, but I'd say without an aftermarket intake setup there's probably no value or gains in running an A/Mkt PF on its own.
I've had an ITG PF on mine almost since day one but nothing's really been influenced. It may just get you very slight MPG gains over a long period of time but apart from that, it's not a noticeable change. It changed my exhaust note ever so slightly, again not enough to notice unless you hear your car outside of the cabin every single day like I do (& the Majority of that is probably an exhaust system that's done 76,000 miles
)
The other fellas will be along to give you more specific advice I'm sure...