.I,ve read through previous answers quickly, but here's my .02c..
I don't believe in strut bars for newer subaru's. If you install one as the only enhancement and feel the difference, good for you, but I think it's a mental differrence. It has to be done as a whole. You have to determine what you don't like about the handling, and/or what you want to do with the car
For example, I find that the MY19+ have a huge weight transfer under heavy braking, and it makes the rear very loose. Personally, i find this borderline dangerous. Body roll is also present, but we have to remember it's a suv, not a sport car. So for me, lowering springs will add a stiffer spring which compensate the weigh bias, and will help with the body roll (stiffer spring, and lower COG). I'm cheap and will not bring it to a track, so coilovers (good ones) are not an option. Overall, this will make my life happy.
Now, stiffer swaybars will help with the body roll while cornering, as it's like the suspension was harder to move (figure of speech). Adding a rsb only will aid with the pronounce understeert he car has, while changing both will keep it more neutral but stiffer. Keep in mind, the good old day of fitting a huge RSB in the back of a subaru to make it rotare like a rwd are long gone with all the electronics it have.
Last but not least: tires. Even with a combination of previous points, if you keep those squishy walled tires, nothing will change. It will be the tire the weakest/sloppy point.
Like I said, my personnal preference ad experience. There is not a lot of performance oriented parts for it yet, but when the newer wrx and sti evolve o the next gen platform, we might get more choice. We are limited, as only the imprea and the newer bodied crosstrek share this platform, and ppl are more prone to jack it up compare to have a more sportier set-up...
