Greetings. Let me first say that I don't really know what a supercharger looks like and have very little knowledge on the subject The reason why I pose this question is simple, a friend has a bone stock 1999 Opel Corsa, the only mod he has is a cone filter, and it was unbelivable to me how drastically it changed the sound of the car. It sounded great,and what I liked about it is that its not a constant drone sound, it only screams once you get higher in the RPM's. Now recently my air filter (stock 2004 MCS) needed to be changed, so I got a replacement flat pad and also got a cone air filter. I got a cheap one because i just wanted to see how it worked & sounded. (I've never had a cone filter before). Admittedly it did feel hot after an hours drive but I was experimenting more than anything, what I found was:
- it did not make the car sound any grumblier.
- it increased the supercharger whine quiet a bit, but that also happens when the stock air filter is removed I assume?. But it did sound good with the air being sucked in and followed by the whine of the supercharger.
So Why diddnt't it work? Why doesn't it get grumblier?. Might be a retarded question but I'd really like to know thanks!

 

The stock filter in the mini IS pretty restrective, that is why a CAI (using a cone filter 99% of the time) is the most popular mod....but mostly for sound...hp gain might be 2 hp....
Foam is lounder in whine than fabric....but the general removal of the box the filter sits in gets you most of the sound gain....
Not sure what you mean by grumblier....filter only filter the air...and to a lesser extent muffles the sound of the sc that is spinning at highspeed....think of it as an aircompressor that is beltdriven...

 

P.S.
Drone is usually on the exaust side...
Safe to say the opel has a turbo? So very different than a beltdriven SC.

 

You are gonna get more grumble on the exhaust side. Unfortunately the exhaust manifold and on back for the Mini is just a big bottle neck and restrictive. Alot of guys start with a aftermarket header and cat back, this really opens things up and lets her breathe and growl a bit. Even a cat-back only will be better and give you more grumble than OEM.

 

You hear the whine, especially in the higher rpms, is because the gears that spin the rotors in the supercharger housing are straight cut, but for most O.E.M setups, there are baffles, and panel filters installed to minimize sound, since a portion of people buy the car without having any intention to mod it, just drive it daily. If you look at your intake house, you'll see ribs, and in the intake box, you may see pieces of plastic, they help reduce the noise by redirecting it. If you were to put in a cold air intake box and intake hose going to the throttle body, you'll really hear the noise after that.

As for grumblier, our cars make a little noise, but having two large mufflers and a few other sound restrictors, it keeps them just quiet enough not to cause droning. An after market setup would fix that, but may cause excessive droning that may become annoying after long trips.