3 to 4 hours a corner :confused2 , 2 hours if there cool.
the rears take longer since the rear seat and trunk liner has to come out for the rear coil overs. the fronts should be fairly quick, make sure they use bmw brake fluid or redline or royal purple if you track.
get stailess steel lines while your at it ad 1/2 hour per corner to the total hours labor.
3 or 4 hours a corner sounds really long, when i did it on my other car is was about 4 hours total for the coilovers. BBK's come with ss lines. I know how to corner balance and all the small other things that need to be done. I just need the amount of time so I can run the total cost. With so many that have done it and with labor rates varying, all I need is what some folks mechanics or personal experences have been in installing BBK's and Coilovers.