You might want to take a good like into APEXI intake filters. They are actually better than AEM and K&N from the reviews I've seen on some of the other forums. Also note that you will have to oil your K&N filter so if that's something you don't want to do go with a dryflow filter.

 

the intake itself could be a cheap one, and 3in is better. then, as the others said, buy a KN, or AEM dryflow filter. Then go for a header and then exhaust... just to improve the "breathing" of ur car. Good luck man!