Hope I wasn't too late--
oops - hopefully my post with the spring part numbers wasn't too late. IMNSHO, i'd cancel the order for the BavAuto springs. I've driven on them once, and seen them on many cars. I feel they drop the car too much, and are made a bit soft for the low ride height. This leads to a greater propensity to bottom - a bad thing in my book. Real short should mean real stiff with some comfort compromises, and BavAuto seemed to go short and soft for comfort and looks. Not my cup of tea, and you'll also need the Bilstein sports with the shorter travel = more $$$.
The MTechs are lower, without being slammed. They are stiffer, without being rock-hard. It remains a compromise spring sold by the manufacturer, but BMW gets pretty close to correct.
If you had not already done new shocks and spent that money, I'd probably go with a full Sachs sporting kit, but to maintain the investment in the new shocks and not break the bank, the MTechs are clearly the way to go.
Take your time - the gap is not pretty, but you'll be past it in due time.
--Micah O'C
'17 M2 6MT, Mineral Grey
'04 330i ZHP
'88 M5 2791445
'92 M5T BL01001
formerly '90 535iM, '92 525iT