so it wont serve a purpose for a ls 6.0
Not necessarily no. Again, turbos are sized based on the engines they're going to be mated with, and the performance objective. If you just want a low-boost cruiser 6.0, then you could probably use it. If you're looking for an 800-hp monster, then no. Here's a good reference for turbo sizing and specs: http://www.enginebasics.com/Advanced Engine Tuning/AR turbo ratio explained.html.