I didn't pay any attention to what was under my original valley tray as far as baffles go, just know that there was a bunch of AFM crap on it. I replaced it with an LS3 valley tray I got from Summit Racing, and I don't recall anything being on the bottom of it. Here's some info for you to look through. And to your question as to why I ran that setup, it was due to the manifold I have. The car is NOT boosted, just NA'd..
https://www.bing.com/images/search?q...m=IGRE&first=1
This is the valley tray I used..
https://www.summitracing.com/parts/nal-12599296