FWIW I had this same issue 2 weeks ago. I could not get the cowl piece to come out (the piece where you will install the "V" end of the M3 strut bar.
I gave up finally and brought it into Matt at Camber-Toe who is one of the experts with the E9x cars. I think he had to remove the wipers to get that piece out. He's done many of these and even he said it was a bitch. I'd call an expert for advice.
Koni sport, BMW performance springs, M3 arms and sways front and rear, M3 subframe bushings, Velocity toe arms, M3 front strut bar, Cobb, ETS FMIC, Wagner catted DP, Vishnu charge pipe, RPI scoops, M3 steering wheel, City Vision angels, CDV delete, Advan RS 18 inch, Pilot SS