Conclusions up to now:
1) If lowering springs are gonna be used, they re better be H&R. They re recommended by most professionals and all the HR owners i ve talked to, they re quite happy.
2) The shocks that will be used with lowering springs, must have a shortened stroke than the original factory shocks. In other words shocks special for lowering, like the Bilstein B8 or the yellow Konis. If standard lenght shocks are used, there is a possibility of bottoming out, and also a danger exists of the spring slipping out of the holder causing the car to suddenly becomes uncontrollable (according to Bilstein http://www2.bilstein.de/en/produkte/faq.php3
). I havent heard anything like that happening in real though. And i remember putting the rear HR sping next to the oem one, and they had the same uncompressed height! So I guess this is a general precaution.
3) Till now, i ve tested in real the following two combinations on a 147:
a) HR + oem socks: Great comfort ride (the 147 TI's comfort improved very much) nice performance but not perfect, it gives a small bodyroll on some occasions.
b) HR + Bilstein B8 (yellow sprint). Fantastic performance, medium comfort, but not
harsh. You ll keep your dental fillings in place. The suspension works up and down as it is supposed to but in a controlled way, you do have the feeling of strong damping at all occasions.
4) All the professionals I ve talked to ( including Bilsteins' Help Desk), they all recommended the following combinations: a) oem springs with yellow Bilstein B6 (sport). b) H&R springs with yellow Bistein B8 (sprint). NOBODY liked the idea of the Bilstein B4 ( all black ) combined with the H&R or any lowering spring. "You do it at your own risk" they said. Not recommened.
I personally would like something in between, H&R springs combined with a set of shocks that will have a stiffness between the Alfa Romeo shocks and the yellow Bilstein B8, but whoever I ask, the answer is the same: "There isnt any". When I ask about yellow Koni, they say that at their softer adjustment, they have the same stiffness as the Bilstein B8.