Why isn't the stock filter enough?
The stock air filter is often made from paper material, and built for assimilating dirt particles for a long period of time. To get sufficient cleaning, the filter is pretty dense, which creates a rather high resistance for the air that is passing through.
Why use a sport filter?
A sport air filter is often made from another material, that more efficiently lets air through. In return, the sport filter often needs to be treated with oil to be able to filter the smallest particles.
Do you need to fit extra air hoses?
No, you don't have to, but its better with cold air into the filter than hot, so it might be a good idea to fit a flexible hose from the front to supply the filter with cold air.
How is the sound changed when fitting a sport filer?
With an open filter, the sound gets a bit louder and sportier.
