No build thread since I didn't really build it. Other than the M3 strut bar, I mostly just replaced stock parts with upgraded parts, where available, when the stock parts were due for replacement. The only significant change I made was go to a square wheel and tire setup with 18" x 9" wheels and 255/35R18 tires all around. This eliminated the corner entry understeer, provided more overall grip, and noticeably improved the cars responsiveness to changes in direction. It also allowed for rotating the tires front to rear to even out the tire wear.
Here's are some of the upgraded parts I installed as it came time to replace stock parts. Most of these changes were primarily to improve reliability. I really liked the car stock and there was little I wanted to change.
Stewart water pump
Rogue Engineering power pulleys (primarily to get rid of the stock plastic pulleys, any power difference was below my threshold for noticing it)
Dr. Vanos vanos kit
GAS DISA upgrade
Install cold weather CCV system
Meyle front control arm bushings
Meyle swaybar end links
Meyle rear trailing arm bushings with limiters
Meyle rear upper shock mounts
Z3 rear shock tower reinforcement plates
BMW front upper strut mount reinforcements
Just remembered one other "mod" that I did. I replaced the clutch delay valve with a Zeckhausen one that eliminates the restrictor. The stock clutch drove me nuts with its built in slip. The clutch on my car is the original at 152k and feels perfect; I think part of the reason for this is the elimination of the CDV restriction.