I got the recommendation re: 29664 springs from a guy on this board (well, he's on this board now) Fitz318is --he had both the H&R sports for the 318is and the #29664s and recommended the latter hands down...
All I can say is that I really like the way my car handles for daily driving on NYC roads, which suck btw.
They aren't the hardest ever... but I like to feel the car get off the control arms and onto the springs when I set the car to turn. I'm a fuddy duddy that way I suppose. (for reference, I've also put off buying parabolic skiis!)
having said that, I *love* the way thumper's car handles on H&R race springs, and no power steering... when I move outta new york and can get a hoopty truck, I'm getting something a little lower / stiffer.