Had a spare moment to experiment with GPS antenna positioning.
I decided to move it out of the boot lid as I will be fitting a gpswart-less boot lid soon.
So i decided to de-lid the antenna and put it in 3d printed box which will be attached with double sided sticky tape:
First fitting location I tried is dash, it would have been mounted under the dash, above the vents:
Second location is rear parcel shelf:
And here's the reception quality in the original location:
I ended up picking rear parcel shelf for it's final resting place.