Air filter box, and filter question..
 

So i just bought a 2000 volvo s40 last week, and there is a sticker on it that says the air filter was last changed May of 2005 at 40,000 miles, it is currently at 80,100 miles. My question is, how often does the air filter need to be changed, and should i just put in a K&N filter instead? Also, i was looking at the air filter box, and the side that is facing the outside of the car there is a hose coming off of the box and it seems to be cracked and fading, i didnt have a chance to take it off but it seems that it only extends a few inches and doesnt lead to anywhere, im wondering if i need to replace it or not or take it off. Thanks :)

It depends on the filter and the conditions but most OEM filters should be replaced every 10K miles.The fact that you see a sticker there on the box only means that someone actually did replace it at that time.It doesnt mean the filter wasnt replaced ever since but not everybody puts a sticker.If it looks dirty then replace it OEM replacement filter is cheap.If you wanna go with the K&N filter you should know it has to be cleaned time to time.
That little pipe is part of the cold air intake system on this car.Trough that snorkel the colder air gets in from behind the fender.Outside cracks are OK unless the pipe is actually broken its still good.

Ok, Thanks :) the filter looks relatively clean, it isnt like dark brown or black or anything like that so im assuming that it was replaced recently. and thanks for the info on that pipe, i was worried that i was missing something on my car LOL. :)