I used it once with an RB25DET Neo, no effect.
A few occasions with an RB30E I noticed an ever so slight improvement in response, but no effect on power or economy.
So I've come to the conclusion that the RB30 being 250,000-odd kms old had dirty injectors.
The RB25 being 50,000km old was nice and fresh and was always run with decent fuel, thus it didn't need injector cleaner run through it.
Correct me if I'm wrong, but I'm under the impression that the way the injector cleaner works is that it alters characteristics of the fuel which causes it to burn hotter, which in turn burns away some of the crap off your injectors, thus cleaning them. So if all you're doing is cleaning off the little deposits of crap on them, then you wouldn't really get much if any noticeable change. If your injectors are really dirty or blocked then the only way to clean them up to remove the injectors and have them properly cleaned.
Whatever your situation, I seriously doubt it's going to give you any more starting line oomph in the traffic light GP