The Rehagen link does say 'quick ratio', but nothing about whether it's any quicker than stock.
Actually, most of R&T's data panels for the S197 show the same 15.6 ratio being OE as Rehagen claims for theirs. There's a 15.7 (2005 GT) that is likely the same unit, and a 15.2 for the Boss LS that may not be (the difference could be in the steering arms/knuckles).
Norm