Originally Posted by kitw
They help but it's not the only way to get rid of drone. The Corsa doesn't drone in the slightest and it uses reflective tuning, rather than helmholtz resonators.
To clarify, you need anti-resonance chambers to avoid drone on the M3. The ones Corsa use are not as effective as Helmholtz, but they do the job. The valved systems can act as a resonance chamber with the valves closed if designed well, so those should do the job as well (and trhey ought to for what they cost
). But any straight-thru system without such a chamber WILL drone; the only question is how bad and at what rpm range. Some folks don't mind, while others avoid the affected range by using a lower gear. A matter of personal preference. I used to put up with drone, but not anymore. Good day gang.