2013 981 driver side rear, intake noise
 

Sounds like possibly an AIR pump type of noise. At first I thought maybe a small hole in the muffler. I believe it may be an electric fan motor as I hear a relay kick on about 4 or 5 seconds after starting the engine. I can only hear this on the left side air intake. What could it be? Thanks!

Kind of the wrong forum for a '13 but hopefully you'll get some help.
Does the noise continue after start up and running or is it just at start up (for 60-90 seconds)?

Try here
https://rennlist.com/forums/981-forum-264/
There seems to be a lot of traffic there.