It's time for another game of What's... That... Sound!!!
 

After some mild driving in the neighborhood, started makes the sound after the engine was shut off. It's done this once before, sounds like pressure is relieving, calms to a boiling sound. This is separate from the coolant filler neck boiling, sounds more towards the overflow tank.

There's a tiny vent hole on top of the coolant overflow that the steam may be escaping from. Pop the cap for the overflow and see if the sound is coming from there.

If so your cooling system is in dire need of attention... is your low coolant buzzer on?

Turbo coolant hoses?

And you definitely need a belly pan. Hard to imagine it's not running really hot this time of year in Texas w/o one.

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First....holy shit that's loud. Is it that loud in person? Where in Texas are you? I'm in Dallas. Happy to help you take a look and diagnose if you're not terribly far.

If the coolant in your tank is boiling you've definitely got a problem. Could be a variety of things. Do you have a linearized temp gauge or an Apexi PowerFC Commander with a digital readout of the temps? When is the last time you checked the coolant level?