If you have an entirely closed system and have gone to extreme lengths elsewhere first: fans, hard drives and heatsinks, then yes it will take that extra bit more off. But then again, if you've been that pedantic anyway with your components why didn't you consider a "silent and insulated" case from the start? There's only so much you can do using this and the performance is ultimately depicted by what case it's stuck into.

The Be Quiet! Noise Absorber kit itself works well, but ultimately it's not a product you should jump to first hand -- prevention is better than a cure, as they say. Compared to Akasa PaxMate at least I'd certainly recommend this in preference, and considering how much some professional matting costs, I'd again look at this as a nice medium. Be Quiet! has currently very few retailers in the UK though, so it might be hard to get hold of, but if it's really what you're after then the more noise you make the more motivation people will have to stock it.

So noise absorption kits might not be the highest thing on everyone's shopping list, but it seems Be Quiet! might have good product in a niche us modders might need.