I used Optimax when I first got the car but now am running BP Ultimate, I get more ks out of a tank even though a give it a bit more.
I have heard nothing but bad things about Optimax. There a few guys at work who had high performace cars, a heavily modded Silvia and an EvoII, and they both said there cars ping and run like crap with Optimax.
I forgot to mention that I asked the Caltex technician what RON the Vortex stuff is and he said it was 96 RON, what's the point?!