I have had the Tein Flex Z's for probably about a year now. I purchased them shortly after being made available. They are without a doubt cheaper than most and after doing some research the reasoning behind it is because they are in no way rebuildable as most of the more expensive coilovers are. That being said, I believe that they offer a lot of bang for the buck. I have installed them myself and have had no issues whatsoever. The ride is surprisingly smooth and it handles much better than the previous set up which were stock springs on KYB AGX adjustables. I'm currently set on 8 of 16 in terms of the dampening settings. All in all, I am extremely happy with the Tein Flex Z's. I would def say that they need to be paired with RUCA's and FUCA's at a minimum if you plan on lowering the car. I've installed SPL RUCA's and Z1 Race FUCA's. Don't forget new paper gaskets as well to avoid the very annoying squeaking. I would buy them again depending on how well they hold up over time. My Z is not a daily driver and sees mostly only weekends and various club Z events throughout the year.