yeh K&N and Apexi are the best two pod filters you can buy
K&N's are legal, not sure about apexi, if that makes any difference to your choice.
i have a K&N and a mate has an Apexi power one and they both seem very similar in noise and performance increase, just remember to take advantage of a pod filter you have to get cold air to it, so remember that when installing it etc cos you will in the end either enclose it or run a pipe from underneath it etc.