Weird DTA compressed file in Mafia

[FitGirl]

LZMA is a solid compressor. MSC_tak operates on chunk level. So you have lots of smaller PCM chunks which are compressed individually, so later LZMA can't do much, too heavy entropy.

As for "why lzma does better on encrypted data" - it just may happen that default ordering bytes (l/b/p options for LZMA compressor) are good for this particular set of data. afair it's 3-0-2 by default. You could try to change those too in brute force and see if it will make compression better.

Try cls-razor on original and decrypted/unpacked data, it's better suited for raw-like data. lolz also may help on some raw-like stuff, but not on all.