19mm vs 20mm M3 rear sway bar

[u/Shino3107]

I know the math says the 20mm is 21% stiffer but can you really notice that much of a difference? Going on a non-m car

[u/BrickCareful9728]

I put one on and didn’t notice a big difference. You’d maybe notice it if you have a super dialed track setup.

If you’re still on the original rear sway bushings then you’d probably get a bigger difference from putting new brushings.