yup, and a lot of that has to do with tuning the exhaust to maximise exhaust gas scouring at lower rpm, improving low rpm flow efficiency while maintaining backpressure, etc., all of which supports locating the cats further downstream and improving the headers.
ps, the quote about both cats being 400 cell was made by JD in a thread from about a year ago, so caveat emptor to all.
Pre-cat bypass vs. secondary cat bypass