Dozens of people run these. Ride quality isn't bad, but any coilovers with dampers properly matched to teh spring rates won't ride "bad"- but stifer springs are stiffer springs. I supervised an install of Tein Flexes in a friend's STi in between autocross rounds- the change in his car was unbelievable, and the ride isn't bad at all. For what they cost, The Teins are worth it.

 

I totally agree, for what you get for with the flex's for the price, it's a pretty amazing little setup. The adjustable dampening on them can really vary the car's performance.

As far as road noise goes, you might notice it a little bit, mainly when you hit bigger bumps and such. But cruising down the highway, it's hard to tell the difference.

Nick