Well, my car is rocking a 2.2. Lol, it's not a Z24 :P But yes, it does only make the sound from 1st to 2nd. I was driving around the other day, no music, windows down. Purposely paying as close attention as I possibly could for the sound, and now I can pretty much predict when it's going to happen. It's always when I get decent acceleration and haven't quite yet changed to 2nd. I would say yes, it does it more frequently if I'm going rather quick for 1st. (30-40km/h)