The 320i is an absolutely awesome car to have a blast in, I would have kept mine, but I just wanted to have a very fast car again, hence the 340i. The N20 / 320i just dies in power past 3700-4000 rpm.
320i N20 w/ Methanol Injection
https://f30.bimmerpost.com/forums/sh....php?t=1508531
IMO, if you are a 320i owner, you do 2 things to the car. 2TB Sport Auto Trans coding & JB4 Map 5. That's it, you'll really enjoy it.
Intake if you want to hear the turbo, and an Axle Back if you want to hear the awesome N20. Deepest 4-cyl I've ever heard.