I think that the car is lowered more than 3 cm with the H&R springs. My car dealer suggested H&R, too.
But if I lower my Space Star, I will buy the Eibach Pro-Kit, like in my Daihatsu. The Eibach springs have a progressive spring rate (unfortunately only in the back for the Space Star) and offer quite much comfort. I drove over a 12 cm kerbstone with my Daihatsu at a speed of 50 kph which killed two steel-rims. But after more than 160000 additionally kilometers the suspension is still fine. The quality of the springs really convinced me after 250000 kilometers in total.
One goal of lowering the car for me is the improved fuel economy .
Mitsubishi Space Star 1.2:
Daihatsu Cuore L251:
__________________________________________
View my fuel log 2015 Space Star Klassik Kollektion+ 1.2 manual: 67.5 mpg (US) ... 28.7 km/L ... 3.5 L/100 km ... 81.0 mpg (Imp)