|
I assume you mean the front suspension arms, and assuming that when you say lower control arm you mean the rearmost (of the front) ones?
There's definitely an advantage to replacing one, or the other, or both of them, compared with stock.
The front m3 arm ('radius rod') has a far firmer bushing at the inner end, which helps a lot with keeping the frond end and steering predictable. Otherwise the m3 rod is identical to the non-m arm.
The rear one ('wishbone') is slightly longer, as well as having a ball joint at the inner end rather than a rubber bushing. The extra length gives approximately 0.75deg less (more negative) camber, which aids front end grip a lot. The ball joint again firms up the front end.
So replace the radius rods and you make the biggest change to the bushing stiffness in the front suspension. Replace the wishbones and you gain a bit of front end grip (and a little stiffness). Replace both (all 4 arms) and you get all those advantages (at the cost of a tiny amount of NVH, but not much else).
|