Apparently these don't have any gains whatsoever for the DOHC phase 1 EJ25 at least. Pat Olsen dyno'ed his with one. Search this forums for his thread.
When they first came out people were nothing but positive reviews about them; now I don't know if that was just positive thinking/excitement over a new part, but more and more less-than-stellar reviews are trickling in about these things.
Maybe you have to be in the right frame of mind to see gains with these things