Collection only.
Item location: somewhere on the westbound M3 between junctions 2 and 4.
Yep, after replacing the downpipes and tightening the nuts to the same torque with my NPL calibrated wrist, one of the two surviving Sandy Bike Spares clamps fractured and then one of my laboriously made replacements fell off.
Note to self: recheck tightness after a few hundred miles.