I think this is more of an alignment issue. Usually an increase in caster makes the car less likely to turn, basically more stability driving straight. If you have a lot of negative camber in the front with 0 toe (or toe out), it will move like how you're describing. The other thing could be the tires. Some tires are more susceptible to like tramlining (ie. Michelin PSS).
I am in the process of upgrading the suspension on my wife's 2003 325i sedan with ZHP parts. I have a complete set of springs and will buy new dampers. FCPro is telling me that there are the correct dampers:317-539 and 317-540 but the link above states that these are the correct one: 317-541 and 317-542. What do you all think?
I am not sure I know the difference. It is my wife's car so comfort has to be taken into account but I found the stock suspension too floaty.
330i Base | Mysticblau | Slicktop | 6MT
The 317-541/542 indicate they are for both the Sports suspension settings (S226A) and M Sport Package II (S338A) the 317-539/540 indicate they are only for the Sports suspension settings (S226A).
Do you know which ones are stiffer? Which ones did you use 317-541/542? These are the ones I ordered