Exhaust tailpipe clamps

[Slobberchops]

The standard clamps don't seem very secure, and I have had one set come off the car. They're twin pipes fitted to a Designtek box on either side.

The clamp is of V cross section but this just doesn't seem wide enough to cover the flange on the tailpipe when mating up to the boxes.

Is there anywhere to get wider ones or are the easy fit ones any wider?

Any help appreciated.