Well, the .45ACP is naturally subsonic, so all you need is some type of mount for whatever can you buy. To me, most cans work about as well as any other, but I'd get a dedicated .45 can (not multi-caliber).
That being said, TSMG is not really a good host for add-ons, and I'd be wiling to bet it's more work than it's worth.
I just bought a M3 and that is easy to work with.