Air filters.

[Arryhall]

Changing the oil and oil filter on my R75, 1.8t, and my mate asked about the air filter and when it had been changed. I actually have no idea! So I thought I'd have a quick look. K&N air filters are well known, but what is the difference really between a K&N and an oem filter? The K&N is designed to last a lifetime of the car, and improve airflow, whereas the oem is a throw away item every...whatever they say is the lifespan.
Thing is, I'm wondering what the difference actually is, and is it worth the extra money? I would have thought that a more restrictive filter takes out more gunk from the air that you don't want in the engine so would ultimately be a better thing for the lifespan of the engine. And if improved air flow is better for the car, then why not go stupid and have no filter?

Not being facetious, I genuinely don't know! All I've heard is people talking about how good aftermarket stuff is, and K&N have been mentioned. In fact, it is the ONLY make of filter I can name!
Can anyone help fill the hole in my knowledge with information and experience? I've google searched but to be honest, I don't know how much I trust some of the stuff I've read.

This is probably in the wrong forum, but I'm genuinely interested as I have decided to actually do things with this car as oppose to paying other people to do things to it for me, then at least I know it's been done (although, probably not correctly!).

[suzublu]

Well, I fitted a K&N panel filter to the original airbox, all fine, no problems, then I tried an induction filter & I love it combined with s/s exhaust, the noise is lovely

[Arryhall]

Originally Posted by suzublu

Well, I fitted a K&N panel filter to the original airbox, all fine, no problems, then I tried an induction filter & I love it combined with s/s exhaust, the noise is lovely

That's looking nice. Bit more effort involved in that than what I'm capable of, but LOVE that stainless battery cover.