Alistair,
I'd actually like the Plus 8 to make more noise...
The dB check at Castle Combe showed a modest 86dB at 4500 rpm.
On the C43 I can have the exhaust noise whenever I want, it has a separate on/off button without engaging the pops and bangs.
I'm beginning to discover that whatever the mode, vigorous acceleration results in a lot of noise!