Anyone use K&N air filters - Subaru Newbie here

[Subadiving]

Guess what@.... My license plate just arrived! Installed it and gain +10mpg and 10HP.... lol .

The handling improved too. How cool is that?

[Seabass]

Oh man. I forgot about this thread and it blew the hell up!

To put it simply, the subaru intake is designed to NOT be a restriction for the maximum MAF that a stock engine will see. So let's say for example that the k&n filter is 20% less restrictive. This is tested at a certain air flow rate that will be far above what the 2.5i or even the 2.5 turbo can flow. At a normal air flow rate, that 20% might become more like 1% because neither filter is being pushed very hard

Let me also put it this way. The 2.5i and 2.5xt both use the same subaru air filter. Anyone care to guess how much power you need to be pushing before the stock intake and filter actually become a restriction? It's past stage 2 which will be north of 250 WHP/WTQ. That's around 300bHP. You might gain 5hp by switching to a k&n at that point. At stock levels, it does nothing but save you from buying new filters. On the turbo engine, all it does is throw the sensor scaling off a bit and make you run a bit lean. If you correct the maf scaling, you end up gaining next to nothing.