I recently went to an auto parts store to purchase a replacement air filter for my 124 300TE 4Matic, and the salesperson tried to convince me to purchase a K & N filter instead of the stock air filter, claiming I'd immediately get better gas mileage and performance, (to justify the triple amount in cost I perhaps?). But since the air filter is housed in a steel case, I'm doubtful of the "more air" claim and even the better gas mileage, though I could use any increase in performance I could get! However, I've heard that the the K & N air filters are not as good as the oem because they don't catch as much dirt. Is this true? Anyone have correct information or experience? Thanks.