Why don't you want to look into H&R coilovers?

 

I am considering H&R Coilovers but I've read that their parts are plastic and the ride is pretty stiff. Do you have any experience wit H&R Coils?

 

While they could be made by the same factory, they are made with different specs aren't they? For instance, the Ksport and Megan models for the same car use different spring rates.

Here's an example ( I don't recall which E60 this was though ):

Ksport:
F - 560 lbs/inch 10kg
R - 504 lbs/inch 9kg

Megan:
F: 6kg/mm = 335.98 lbs/inch
R: 6kg/mm