Hi have to chime in on the K&N filter thing.

I have two of them on my Legacy.  I did away with the butterfly valve and just have a big 'ole K&N hanging on the end of the induction tube in addition to the filter on the side.

I get at least an inch extra of manifold pressure on take off.  I really think the pressure rise on the inside of the cowling when going fast is as good as the ram air tube by itself.

Just cleaned my K&N filters, lots of dirt came out, no noticeable damage to the filter element.

I think having a big K&N plus the one that came with the kit allow the air to move slower through the filter element, making it much harder for the engine to damager the filter via vacuum.

Just my random thoughts on the subject.  I think the K&N's work just fine....

Kevin