I'd be interested in this thread. I have the same car M-Tec II 530d and she is coming around to needing a full corner refresh - arms, balljoints etc - I'm trying to work my way through the linkages and joints, then when they are good, gonna put a set of shocks in her - I'm happy enough with the stock M TecII ride height, as I'd probably be bottoming it out and ripping belly pans of it if it was any lower.
Anyway - I believe from the bilstein literature that B4's are rated at SE ride height, and that the operating window in an M Tec would be lower than this - hence the B6 model which wouldn't bottom out in an M5 or MtecII. I'm probably going to re-use the factory springs. In other words, Bilstein reckon the B4's wouldn't work / last at MtechII ride height.
Anyone been down this road before and know from experience what works and what deffo doesn't - specifically will the B4 shocks work at MtecII ride height??
Have a nice set of M5 rims to go on her when the suspension merits them and a decent set of tyres.
Cheers lads