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."
Mods-Etc: Quaife LSD w/VAC finned diff cover, M3 Rear SF Bushings, M3 sways & OEM Susp Front/Rear Cmpnt Kits ('cept strut brace), GC Caster/Camber Plates, AC Schnitzer M3 Sport Springs, JRZ RS1 dampers, JBD 100%, Goodrich SS brake lines, non-stggrd APEX ARC-8 18" wheels with Nitto Motivo tires (winter OEM 17" wheels and Blizzak LM-25).