BURT150 That looks nice , Subtle :thumbup: Ive fitted a few parking sensors at work and iirc the artermarket kits are 20mm. You normally get a little hole saw with them. If the holes you already have are 24mm you could use the hole saw and drill 4 bits of aly or plastic then bond them in behind the bumper then push them in after :thumbup:
JohnnyN A £1 coin is 22,5mm Dia. A 10p coin is 24,5mm Dia. I would estimate that those holes are roughly 23,5mm. If you get some that are bigger you can always open the holes up slightly with a Dremmel or such?