I have to imagine AMG's air filter is pretty efficient. Replacing high performance OEM air filters often yields little, if any, improvement to cooling. In fact, in a few instances, I've seen independent shops determine that certain aftermarket filters are actually LESS efficient than the OEM units. I'm not trying to dissuade anyone from doing this -- just advising you not to expect much of an improvement.
A few years ago, I was talking to the guy who owns the tuning shop that did some work on my Volvo. I did a bit of research on the springs I was having them install but still asked the owner whether he'd heard any complaints. His response was interesting. He kind of laughed and said something like, "I've been doing this so long that I've found, more often than not, anyone spending this much money on a mod tends to be happy with it." In other words, most people aren't objective about it -- they're just excited about the fact that they're modding their cars. We continued the discussion and he completely agreed that every mod is not a good mod. And, in fact, I knew at least one person who disliked the springs on his car (although we later learned that his car's suspension may have had a distinct set of problems). And, for what it's worthy, the springs were worth every penny. lol
I kind of look at air filters the same way. It's a cheap mod. Every one can afford do it. People who mod are happy to mod. Their "butt dyno" tells them that replacing a piece of paper between the outside world and the intake made their car faster and louder but, in reality, it's mostly (if not all) in their head. I've yet to come across any air filter that truly yields a different engine sound (it's always, "watch this video....aaaaand, there, did you hear that intake sound?...no? okay, go back and play it again...wait, aaaand...hold on, I missed it go back and play again...okay, listen closely....there it is...isn't that awesome? No, the OE version doesn't sound exactly the same!") and to the extent that the aftermarket filter is more efficient than the OEM unit, nobody's butt is feeling 0.3% increase in HP.
Replacing the whole intake system might improve performance slightly (provided the new intake doesn't actually pull in more hot air) but I wouldn't get my hopes up over a filter.
Thanks,
-Eric