@wallenieswiftie - I own a 2011 335i with M-sport packaging. Unfortunately this was mainly a cosmetic treatment in 2011 (and offered only in 2011 if I recall). I don't believe anything was altered from performance/dynamics perspective. Those being "M-style" air dam, rear diffuser, rockers, and if from factory the black headliner.
It remains a fantastic everyday driver I intend to keep forever (God and supply of parts willing). This was the era of peak BMW in my opinion.