So I'm thinking about an air filter for my evo but I have no idea what I'm looking for to be honest. What has anyone else done with there's?

what engine?

1.4

BMC panel filter or the K&N Filter if you are after a "performance" filter...

Go with k&n one its £35 and will never need to be changed have a look for part number on site theb search for that unlikely to give more then say 1or2bhp.

Cheers guys

Waste of money.
Everything less than 10 hp is not noticeable, only in your wallet..!!
Stick to original, or quality aftermarket paper filter, change when necessary, and forget all the "sporty" airfilter gimmicks.

Thats what I was saying the k&n oem style filter is £35 and will save you money in long term.

Nothing can compare airflow of a new, clean paper filter, not even K&N, they admitted this fact themselves..!!
So if it's REAL performance you're after, stick to the factory filter, and maybe change it a bit more often.
(On the other hand, if you're driving a big, carburetor equipped V-8 in dusty desserts, you may need K&N...cause that's what K&N is designed for in the first place, in our cars, it brings nothing but noise, complete waste of money)