Yeah, I like my B12 tuning kit. It's bang for the buck IMO. Lowering springs with matched sport shock and only cost US$730.
Performance wise, it's a big improvement. It used to be abit bouncy on stock suspension and now it gives me much more confidence in corners. It's like riding on road rail now (maybe my wheel and tires also contribute to that)
It's stiffer than stock and ride is abit rough but it's still not that bad maybe it's because our roads here are very bad.
For the PSS9, you get height adjustments and stiffness adjustments so you can dial in your car to your style. I have heard alot of positive feedback on this coilover but they are expensive.
Hope this helps.
