Mine had the gurgling kit installed with a recall (I suppose). I removed the entire thing (tubing and all) when doing the oil-to-coolant oil cooler replacement/repair.
I heard the gurgle a couple of times, then it quit. The problem is: the top of the heater core is the highest point in the cooling system. Any air in the system gets trapped there, and it will gurgle until the coolant flows thru for a few minutes and fill the core completly with coolant.
My MKIII Toyota Supra does the same thing, and is common to that model. Much air bleeding is done by Supra owners to remove as much air as possible from the core.
But.....when coolant gets hot in the engine, air bubbles can form in the coolant (oxygen seperates out), and the problem can come back.
I've learned to live with it, as it only lasts for a few minutes at most.