You've begun a great start by simply reading the thread-thank you. I'll chime in with my 2 cents worth. As you know I started the thread and did my best to coordinate and keep it moving along-with that said it was frustrating as many aspects were out of my control. I can say the end results, measured with a bang for buck meter, are [also my opinion] worth it.
If I had a do-over and was beginning my LS-x swap I would do it again-albeit a slightly different outcome as I posted in #400 [see below]
If we could have a do over then I'd personally do the following;
Have the oxy sensors bungs shipped [but not installed] then, drill holes & weld in best position/access/clearance for my z
delete the v-band connector on headers
shorten or angle the collectors [primarily the right side] more toward the tranny
weld a 3" to 2.5" transition directly to the shortened collector and v-band at the 2.5 end [better clearance in the trans tunnel]
sell my entire old 304ss exhaust and go aluminum after the 2 to 1 junction using a b-v-band connector [losing a few pounds]