MBRP Clamp issue help.

[Mcq1134]

So the exhaust has been great for about 6 months just recently I noticed on cold starts and when you put the car in drive when its still cold or medium warm you can hear a clamp rattle directly under the rear driver side passenger door. you can only hear it when you rev anything up to 2k or less but I do not hear any of it when driving or with the door shut. I took it to a shop for an oil change they looked at it tightened the clamp was good for a day or two. This issue is only on the left side. Goes away or I can not hear anything when the car is warm if I return home after its warm and do some revs cant hear it.
Any recommendations for new clamps I can buy? or should I have a shop weld where the clamps would normally be?