Did this mod about 2 weeks ago. Haven't had a chance to drive my car that long with the exhaust but it's not for the faint of heart. At idle, you can tell something has been done. It is considerably louder than stock at any RPM range, haven't had a chance to go WOT yet. If you manage your RPM's (aka keep them under 2k), you can get around town quietly. When I'm driving normally, I'm between 2-4k anyway so it's not too bad.
There is drone though, no doubt about that. Not all conditions of course, but it's there, which is expected. For example, fourth gear, going up a hill, there's enough resonance to make some clips rattle in the headliner rattle too.
Going muffler delete is probably the easiest route but:
- I think it'll be louder than this mod, which is about as loud as I want to go (yes there is something as too loud)
- This is just a theory but I think the chamber in the middle still absorbs SOME sound and drone. Just my guess.
Current: 2008 BMW M3 Sparkling Graphite/Bamboo Beige/6MT. 1999 BMW M3 Techno Violet/Dove/5MT. Next: 2017 BMW M3 CP