[r33_RGSport]

Man, this thread got out of control. Specs wise, lol.
I don't understand why the Admin didn't separate M8 and 8-series forum, but they did separate all the others. Even down to cosmetics mod, suspension, etc into all little sub-forums.

Anyway, OP's question is totally irrelevant to what i've done to limeypride 's F93 M8 GranCoupe. Spring and Spacer setup will not applicable on G16 8-series GranCoupe.

M550 spring that M5 guys been using are from G30 M550 specific spring from H&R.
Again, this won't apply to OP's G16 8-series GranCoupe.

Now, the specific spring for G16 8-series GranCoupe by H&R.
To answer your question, no, I haven't install it since not many 8-series comes around yet and H&R just recently released the spring. Probably less than 6 months.

Spacer wise, as I discussed with OP through PM, my measurement is at stock height.
So, you'll need to measure after the drop, because most likely it is different than stock height measurement.