I have the K & N and have had no problems also. In the beginning I also cleaned up some light oil from the bottom of the air box due to the filter being over oiled from the factory. I have pulled out my MAF several times just to make sure there was no oil in there. It was completely dry, no oil residue what so ever.

 

I got an HKS drop-in filter, a better upgrade than stock.

 

Perrin also has one, foam type. World One has it for around $35 or so. Cheaper than any other I have came across. I don't know anything else about it though.