Im debating on getting the K&N for the mazda3, i had them for my tbird and mustangs and it made the car a little louder and slightly better performance. Anyone buy one and can tell any difference in gas mileage or performance\loudness? I know it will probably pay for itself in 50,000 miles (5 normal filters) but I may jump to the mazda speed or another mustang GT by then, so im just wondering what you guys have noticed. Thanks.