i like those stainless steel band clamps. the ones that are 3 or 4" wide, tightened up with 2 bolts & what ever dia. pipe ya got.
make sure everything is clean & smooth & let everything settle into place assembled. run ya a bead of sillycoon around the joint, install the clamp & tighten till the 2 end parts come together or bolts break, which ever comes first, lol.
should have no leaks. plus a good lookin clamp.
have used some tail pipe expanders over the years. usually do a good job at cleanin up the end of the pipe. stainless steel is tough.
be sure to get some anti-seize or moly paster & slick up all threads & the wedge part. helps make the job easier & make the tool last longer