Toine, It was my daily car too and the sound was deep but not intrusive. Just a thought.
LHD or RHD? Mine is LHD, side exhaust would be poking in my ear and I don't know if it could be MOTable.
I replaced the original exhaust line because it had holes in the middle box... I thought about just cutting it off and replace it with a pipe but been told it's a NO for continental MOT. BTW the orginal exhaust line had that kink/bend. (dealer said it wasn't an orignal Morgan part but...hey.... the car has always been serviced at his place since 1985.)