If your using a cone filter make sure you make an effective heat shield. Without a heat shield the cone intake is worse than your stock airbox. A lot of people buy K&N cone filters because they growl more when accelerating. It will make a hissing sound too.
As for power gains on a "stock" motor, there's barely any. If the temperature and humidity outside is perfect, you will notice the car pulls harder at night time when the air is cool and there is low humidity. During the day driving around the city at 60km/h or less, you'll probably notice a slight power loss because your sucking in hot air from the engine. Your car will feel sluggish.
The cone filter is commonly known as the "racing" air filter setup because when your racing on the track there is a constant supply of fresh cool air from the outside. In most cases a heat shield isn't needed. But for street use, a heat shield is a must. Otherwise I suggest just using a drop-in filter.
With the drop-in filter you don't get the growl you would get from the cone filter. Another downside is the smaller surface area of the filter which is restricted by the stock airbox. A cone filter is also referred to as a free flow filter, there are no air restrictions. But protecting the filter from the heat produced by the engine is a major concern.
'02 C32 AMG / '07 C280 / '07 CLS550 / '15 JKU Rubicon
Last edited by Autotechnica; 01-03-2004 at 04:25 AM.