Anyone using Doug Thorley 323Y-C headers?

[OKGMC4]

I see most people get the 324Y-C headers that are 1 5/8 primary and 3" collector but they make a 1 7/8 primary with a 3" collector under part number 323Y-C. Seems like most of the LS engines (LS1, LS2, etc.) like the bigger pipes so it would make sense that a 6.0 or modified 5.3 (cam and ported heads) would work well with these. Any thoughts? I'd really like to see how they fit in the frame.