So I have a 2004 R50 and am looking to get the nice power gains of adding a header, high flow cat, and exhaust. However, I have built cars before that got that crappy drone noise that starts sounding more annoying than cool very quickly. While this car will be an avid autox'er it is also my daily, so I just want the additional hp that the aftermarket parts provide, none of the sound.

From my research it looks like the Milltek exhaust is the quietest (anyone agree or disagree?

However, I can't really find any info on which header is the quietest, anyone have any opinions on this?