Hi, the opening in my garage door measures 33” wide and 45” high. There is a couple of inches spare height wise when I put the bike in so could get away with say 43”. I do have to remove the mirrors but that’s only a 30 second job with a 14mm spanner. I do however have to give the bars a “wiggle” to get them through the door. Again, you could give them a slightly bigger wiggle to get them through a slightly smaller gap.May I ask you on the dimensions of your Burstner garage door that you put the 390 in.
May look at one myself IF it will go in my garage (but it’s unlikely)