[Lancelot]

I've put together a table of the available ARBs for our platform, BMW has quite a lot of options depending on engine, suspension, M Sport, M Adaptive or standard.

In a nutshell:
- 6 cyl get weaker front bars than 4 cyl engines
- M Sport has slightly stronger bars front and rear
- 440i LCI have stronger bars (same as M235i) than non-LCI 435i
- Xdrive have weaker front bars but same rear bars.

Aftermarket:
I've tried the H&R but they're too stiff on the rear.
I've now put on the M235i bars now and they're too weak on the front.
The sweet spot is probably the KW or Eibach, which I might try next.
(I always put bars in pairs because they're designed as pairs)

Some vendors (Hotchkis, Dinan) have hollow bars so you can't directly compare diameters with plain, non-hollow bars, hollow bar will be weaker than plain for same outer diameter.

Hope this helps...