Placing "MP3" before or after the title makes it clear that the file format is an MP3 [1, 2].

Does this text need to fit into a or a larger paragraph ?

Alternatively, if this is for a button or a direct instruction, you could use: "Download 'Say 123548 (1)' (MP3)"

MP3 is an acronym and should be capitalized [2, 3].

The most accurate and natural way to write this would be: Key Improvements: