Are there any special requirements for a replacement stock air filter or can I throw a KNN in there with no repercussions?

You can put a K&N if you like or stock no big deal
I am not a fan of K&N but sure go for it

No repercussions. K&N is better than stock and you can clean it every year and save money.

Are there any special requirements for a replacement stock air filter or can I throw a KNN in there with no repercussions?
Here's some interesting reading on air filters. The K&N filter is one of the filters tested:

http://www.bobistheoilguy.com/airfilter/airtest3.htm

Sure is interesting. Thanks. i like k and n better, just a prefercne. I don't know of any scientific proof that says its better than every other type, i just got tired of replacing the mann air filters every 12 mos. :)

i like my kn cone on e21 but i totally believe the one on my tacoma could be slightly affecting the maf which is a tiny wire that in my opinion could easily get some oil on it and not work entirely correct. very important to let kn dry out thoroughly after purchase or recharge

see, everybody's got their own opinion about the filter. It's as though scientific proof doesn't even matter so long as there's a stubborn human being out there to say, "BS--I like my K&N, or i like my amsoil one, etc."