M3 seat swap into 330i - SO happy...
For the longest time I've wanted sports seats in my 330i, but there were none to be found...then I found some E46 M3 seats on Ebay. I snatched them up, but it turns out the seatbelt attaches differently.
Long story short, I figured out how to swap the seat rails, and now I have M3 seats installed in my 330i. (Note the standard 4-spoke steering wheel but the obviously sports seats).
These seats are sweet. Obviously, they have the extra bolstering like the 3-series sports seats (maybe even more), but in addition, the back bolsters are electrically adjustable. They have more controls and adjustments than I can name. The bottom line, however, is that they plug right in and work like a charm with no problems---so if you have been considering a seat swap, be advised that M3 seats will work in addition to 3-series seats. They're interchangeable, and I'm driving the proof.
The only downside is that the leather is ever so slightly darker than in the 330i, but once installed in the car I can barely even notice. And the improved comfort and especially stability and security while throwing the car around in corners is just great. It's just what I wanted: a 330i with sports seats but no sports suspension or special tires. Ahhhh!!