I installed them a week ago with the original sport suspension (red) shocks that came on the car and an S4 rear sway bar I had laying around. I really wasn't expecting much from them, having done cheap "spring only" upgrades in the past on other cars. What you usually end up with in that situation is an oversprung, underdamped mess of a suspension that is bouncy and harsh at the same time.
But, I've been driving the car for a week like this and I have to say Tein really nailed this spring upgrade. It works almost exactly like the stock sport suspension, but nicely lowered. The only hint that something isn't stock is after larger bumps at higher speeds, you can feel the front of the car lowering itself back down after extension. It's very subtle, and most probably wouldn't notice it.
One other concern that some have with spring only upgrades is that the stronger spring overworks the stock shock, wearing it out prematurely. I'd be willing to wager that these springs are so close to stock rates that the stock shocks should last forever. I was also concerned that a lowered spring with a near stock rate would have the suspension bouncing off the bumpstops all the time. Not so, unless you're really abusive and doing something with the car you shouldn't be doing anyway.
I just wanted to pass the info along. If you want to lower the car and keep the stock ride (and a pile of cash), the Tein S Tech spring set is the way to go.

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