Originally Posted by vantagesc
I would want the sport seats, but that's up to you.
1) No. Installing the M pieces is just something people figured out, it's not part of any official BMW program.
2) Correct. Though at least on the 135i, if you are starting with the sports suspension, then the cost of the PS is a little less b/c you don't have to replace the rear anti-roll bar.
ZSP/ZMP on the 135 also includes the Oil Cooler. ZSP/ZMP is a must on the 135 IMO.