what are the advantages if any, if you run a sti manifold setup?

It is red. That's all. Unless you will get V7 manifold with TGV-less risers or V8 riser-less manifold. Then, it is a bit better than stock. However, you can get TGV-less risers from a JDM STi and they will work with a stock manifold.

hey thanks for clearing that up!