restaurant style iced-tea (home results dont come close)

I am an iced tea lover. However I rarely can get the taste and
consistancy that I find at restaraunts, such as TGI Fridays etc.
I tried Lipton and Luzianne. I tried brewing the tea using a tea
kettle and pouring over ice. I also tried using my coffee maker.
Does anyone know the blend of teas commonly used in restaurant chains
for iced-tea and what their secret (if any) for making great tasting
iced-tea.
Thanks