B5 likes a lot of rear sway bar. So any of the 25mm rear bars are a good match for sport springs. Popular items are 034 motorsport, Hotchkis, H&R, etc.
Example, 034 Motorsport Rear bar:
https://www.034motorsport.com/034mot...djustable.html
However, the rear subframe area where the sway bar bolts onto the car is relatively weak and not well supported on the B5. So it is highly recommended to add a bolt-in support bracket (or weld in such a support out of steel yourself). Without this you can crack the sway bar mounting area right off the subframe.
Reinforcement Bracket:
https://www.034motorsport.com/billet...4-quattro.html
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