Yep, you need a TC, and quick!!! You can use the one that they put in the 6.0 that is suppose to be a more heavy duty unit for around $400. This is what I would do, then when the tranny goes call Brian at BTS.
Go to directfordparts.com. I had the exact same problem. replaced with a OEM TC and since I'm running stock I saw no problem. I was very surprised by the difference. And the price won't kill you either. 325+100core+shipping. Core is returned when they receive it back. They are part of Gaudin Ford in Las Vegas.
Chances are your t/c is fine, so long as you are not getting any slippage or excessive temps. Like was said multi disk t/c's are more noisy than a stock t/c, some more than others. I have no experience with ATS products but I have a Precession multi disk t/c and it is rather noisy. I suppose you could get a single disk t/c and that would be more quiet.
Other than the t/c noise have you had any other problems with the ATS trans or t/c?