Originally Posted by OldMan335dOwner
Thanks, sorry for the flurry of emails, but being retired I have more time to ponder. The reason for all this is I rode in a fellow 335d owner's car the other day. He had the Sports and M-Sports packages. I liked his ride a lot better than mine. I am trying to find a way to get there without going overboard. That's why I was exploring the H&R sway bars. But that opened up a can of worms, as the Turner web page suggested I should have beefier springs or the H&R sway would be overkill and not a good match for my existing springs. They actually wrote "For a E9X non-M street car, with stock or sport springs, we would probably recommend a stock M3 or the E93 M3 front bar because we know it works well in this application and it's guaranteed to be an improvement with minimal downsides."
The M-sport package comes with stiffer springs and better dampers than the sport package (which is obviously upgraded over the non-sport package). I am not sure if the M-sport package comes with beefier sway bars than the sport package, but the sport package does have beefier sway bars than the non-sport package.
The M3 sway bars are a very popular option. The rear sway bar requires the subframe to be dropped, an involved process, so many people who upgrade their sway bars also choose to swap out the subframe bushings for the M3 subframe bushings at the same time.
If you were to swap your springs for sport springs, M3 sway bars and M3 subframe bushings, you would notice a huge improvement in how your car drives.