I have them all. My personal experience with the new OS VX (Thorjet - Weston mini-pipe) is it does not have the same power as the K&B 48 (Turbax - Weston mini-pipe). The OS does tune easier and will run to max RPM right out of the box. The K&B takes a long break-in and may need a bit of modding to keep the low end disk from turning but, in my experience, consistantly out performs the OS. Also, I haven't met anyone who has had long-term success with the new OS... hopefully, a few folk will post their experience here.

With that said, availablility is most likely what will make your choice for you.

Mark M.