H&R sway bars

[Dan (almaden)]

I am planning a redo of my suspension soon.

my current plans are for Bilstein HDs or Koni adjustable gas sports on the front and Bilstein HD rear. these will be used with Eibach or H&R lowering springs.

I will also do the sway bars and have noticed that the RS sway bars come in 24 and 18mm sizes for front and rear. While the H&Rs are 24 front and 26 in the rear.
Are the H&R rears made of a more ductile metal, less torsional rigidity or hollow?

any comments on any of the above combinations would be appreciated.

thanks