Just a thought -
A muffler shop or a $13 Harbor Fright exhaust pipe expander can expand the foil tube a bit.
But since it’s only a matter of 2-3mm (1/8”) maybe using the top of a FULL water bottle (or something similar) can slowly wiggle that thin aluminum foil into size just enough to get it started on the coupler, a little silicone on the coupler helps too. It’s worth a shot and the general idea is to get than extra width.
A firm plastic bottle or better yet, a
glass might be best as water bottles tend to be flimsy.
You might be able to flatten the coil ridges to gain a mm, the area where the band clamp will cover anyway.
