They wear an in house custom pre-stretched set made from BCY 452X material. Extremely low creep , fast and quiet. I like the factory strings alot and when I have needed to replace a worn set I replace them with the same ones from Bowtech.
They really are a good set of strings.

Here's a link to BCY's website and the specs on 452X.

http://www.bcyfibers.com/technical_sheets/Bowstring%20Material%20layout%202.pdf