nice i did the same upgrade, you will see a vacume solonoid on the reaer of each exhaust, switch car into sports plus engine mode and they will open (shine torch in exhaust) then just cable tie
increases the tone on normal driving, im looking at spacers and lowering debating on:
10mm front & 12mm Rear
12mm Front & 15mm Rear
Eibach gives a nice drop with 20mm all round and keeps the ride almost OEM (did this on my 640 below)
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Current: 2017 M6 Gran Coupe
Previous:2014 640D GC 383BHP + 733NM, F10 2010 530d 520i (2000), E36 comact 318i, E46 M3, E46 318Ci, X5,
Non BMW: 5x Skyline / GTRs, 5x Supras, 2x Nissan 200sx s14a, lots of other stuff