Subscribe to download
In The House, In A Heartbeat KovSky Remix Escape Music (LOUDER)

This mod has a perfect loop, although the way that the L4D skinonourteeth.wav works may interfere. Your mileage may vary.
Inspired by http://steamproxy.net/sharedfiles/filedetails/?id=648548991 .

This is the louder version. Click here to go to the normal version.

--

Original song by John Murphy, commonly known from its appearances in 28 Days Later.

The loop is between 2:19 and 3:14.

Note that to make the loop fit to the original skinonourteeth.wav, the song's tempo had to be increased by 8%. This does NOT increase the pitch, just the speed!
Test out the addon yourself to see if you like it, Parish's Bridge finale map always works.