Amazon has the K&N drop-in filters for the STi for $28.55 shipped: http://www.amazon.com/gp/product/B000BR51EW/qid=1135365775 They are usually around $45 + shipping from other places. Amazon carries all K&N filters. Just check out the application guide to find your filter: http://www.knfilters.com/search/appsearch.aspx and then remove the dash from the part number to find it on Amazon's website. -- Brian
I know that K&N filters are a touchy subject for some, but the car needs a new one, so I think I'll just buy one and see.