[rrfitness20]

Have a 20 M340i Rwd. Lowered on dinan springs/bump stop and have a small 5mm spacer upfront. Have 19x9 square HRE wheels. Tires 235/40 fr 265 35r . I've had my car aligned 2 weeks after my springs were installed and does not pull to any side.
But when I'm going high speeds 90+ the car feels floaty/light. Doesn't feel like it's on rails in other words. Not sure if any of you have experienced something similar.

[rostrata]

Add a splitter, first and foremost. And then work on downforce. After that, possibly stiffer bushings and such for the suspension components.

Personally, I've had no issues with the floaty feeling all the way up to 160 which is the fastest I've taken it with duration. Aside from a tune, my 340iX is stock. Of course, I can feel the lack of downforce but it isn't terrible on this car. If you plan to live at 130+, highly recommend aero mods first. The real ones, not the 3M taped bullshit.

[rrfitness20]

Not sure if that'll resolve the issue. I already have a genuine M splitter with carbon accents
Purchased and installed by bmw dealership