Just got headers installed....

[2011 gtcs]

Update....the combo I have with LTH headers and X pipe with the Ford Racing mufflers is ear shattering loud if you are behind it when you rev it....3000+
Up to 2500 rpm you are okay inside...then things start to get loud.
YMMV.

I have that same axle back with ARH headers and a OFR X-pipe, it's insanely loud, but it sounds awesome.