Personally I think this info should be put in Mr. 5's Sticky but it's closed. I was curious about the OEM springs and their part #'s / labeling after reading through a thread.
I think there should be somewhere the info below + the rest of it completed for 6mt's, etc is posted to reduce confusion as I found it helpful.
Courtesy of member MaverickBMW:
E91 328xi with Steptronic - I2
E90 335ixi with Steptronic - I3
E92 335i with Manual - D6
E92 335i with Steptronic - D7
E93 335i with Steptronic - D8
E90 335D with Steptronic - D8
07 E90 335i TiAg