I had a K&N drop in filter in my 535 and I'll be damned if I could notice any sort of difference in either sound, performance or anything else. I guess the added benefit is being able to clean it and not replace, but overall, at the price of the filter + oil for it, you can buy like 4 or 5 OEM paper filters, which will probably outlast your ownership of the car.
If you can buy it cheap, do it, but otherwise I really wouldn't bother. |