Actually if we are talking 800's with an LS platform, that y pipe is beautiful! I have one from a 2000 4.8 2wd and the pipe is MUCH larger and it has nice bends.
I've actually never seen an 800 Y pipe, the one I'm referring to is this little guy. #5 on the diagram. (Sorry, I couldn't find any real pictures of the part on Google and my V6 truck is in storage right now.)
You must be registered for see images attach
It's definitely nicer than the half ton 350 Y. Still some questionable areas, like where the head pipes combine right before the cat. I ended up replacing mine with Magnaflow part number 23457. Basically the same deal, but with slightly nicer bends and junctions.