Fair enough. Chrisxn...in my personal opinion you will be unlikely to notice the amount of power that an upgraded airfilter will give you, it is often just done for the noise difference.
A cone airfilter on it's own can also degrade you're power rating due to the fact that they're often ill-placed and just suck in all the warm air from the engine. This is bad. I'm sure you understand the reasons why but I'll include them for anyone that doesn't understand and doesn't want to ask.
Engines rely on a healthy mix of air and fuel, without one or the other the engine won't run, engines are designed so that the more air that is sucked in, the more fuel the engine will deliver, hence giving you more power. If you go right down to the molecular level, warm air molecules are larger than cold air molecules, thus meaning that the colder you can make the air, the smaller the molecules are in size, and the smaller the molecules are in size, the more air molecuels you can fit into the engine at one time. So...the colder the air the better. This is one of the advantages of Nitrous oxide....other than the fact that Nitrous Oxide burns much hotter than fuel, it is also extremely cold which cools the air flow and thus fits more air in.
So....removing your airpan and sticking a K&N cone on top of your throttle body is not going to give you any power gains because it's a non-enclosed filter which is sucking in all the warm air as it's right above the engine. This is why many people re-route their air filters to behind the battery as it is cooler over there. I don't know all the technical names for the styles of filters, but to increase power further, would be to enclose the cone in a box, then have a cold air feed coming from the front of the car leading directly into the box, this will give your filter optimum 'coolness'. The other thing to think about is where to locat the filter, lower down is cooler, but at the same time you run the risk of sucking in loads of water if you hit a flood.
As I mention you probably knew all that, but thought I'd post it up in case some people didn't.