Typical off the rack exhaust issues.
Finding an exhaust that fits,works well and does not leak is like the holy grail. Does not matter what you pay or who's name is on the pipe.
Sorry but a tube of sealant is not a good sign of a well made exhaust. Ducati performance pipes used to have a tube in the box
since termi makes most of the new dp systems , no sealant. You need to get our own.