I agree with Waynne. A drop in panel filter will improve breathing slightly over the standard item without introducing loads of extra induction noise. Also, it keeps the car standard for insurance purposes.
K&N and Pipercross are well known brands. Also, look at ITG filters. They use an innovative open cell foam construction which is said to be superior to the cotton type. But then, they would say that, wouldn't they?
I am stuck with second user warranty on my car, so I have to use Peugeot parts for now, but once that's expired I'll be fitting something a little more interesting. I really need a washable filter as I'm replacing mine every 6000 miles at the moment! It gets costly.