I have an 2014 BMW 228i M-sport no THP. I just recently participated in Dinan R&D program, they have installed new springs, bump stops, and sway bars for my car. My Impression when I first got the car back was "wow". It felt like a new car to me (it could also be I haven't driven my car in 2 weeks and having BMW withdrawal lol), with the new springs the car drop 1/2 inch all around and the ride quality was better than before. Before my car driving in comfort mode, felt like it was a bit bouncy; now that bouncy is less. Driving in sports mode felt great, the tires were more planted to ground, also I could go into turns at a higher speed and out.
I was getting some slips also from going into the turns because of the current tires I was running, RFT tires not that great of grips...
From just installing the springs and bump stops, I think it improve the car handling by 75% of the problem and another 10% from sway bars. The setup of the sway bars are soft in front and hard in the rear if anyone is curious. I am also a noob on cars, so don't take my word for it on how much it improves; you have to feel it for yourself
.
This is the only picture I have of my car with the new springs, there will be a better picture on Dinan site later on.