No, *Engine mounts*.
The Mini turned out a bit louder than we expected, despite the tons of Dynamat and plush carpet. Very frustrate.
A few changes improved it a bit (sealing the exhaust slip joints with maniseal, removing the lower engine stabiliser, lowering the idle speed) but the engine vibration was always present- with a particularly obnoxious resonant boom at 1100 and 3000rpm.
At a Mini club meeting Simon from Minibitz pointed out a couple of cars that were buzzing the same way, and he had a theory- recent genuine Rover engine mounts were of poor quality, and the rubber was too hard. Cars with new engine mounts (like ours did) had this problem, while cars with old mounts didn’t.
I fitted a pair of the new mounts yesterday. The difference is miraculous. It’s still a noisy little box from the 1960s, but it’s no longer deafening. The steering wheel doesn’t vibrate, all the dashboard rattles have disappeared, and we can drive at 80kph (3000rpm in 4th) without our heads imploding.