K&N Air Filter: This is the easiest upgrade you can do. It simply replaces your stock paper air filter with one made of improved materials. And even better is that it's washable. You simply wash and re-oil your filter when it becomes dirty, which is typically 30,000 to 50,000 miles. Cost is around $45.00 and is available from most PEP BOYS and other auto parts store. If you cannot find it locally you can order it from JEG's high performance at 1-800-345-4545. Also check out K&N's website for lot's of information at http://www.knfilters.com   Expect a 4 HP increase with this product.