Oh, so that's why! Guess I will be good to go without the lower support then, just shorter bolts (grade 8.8 or what I can find on the "good" shelf at the local hardware store). If anyone is of any other opinion, let me know before I get it powdercoated this weekend
Also might have figured out the front supports, those seem to be for counterweights on non gtr 32's (according to nissan fast).
Some conclusions comparing BNR32 and S15 subframe;
Lower arm position updated
Reduced weight, diff bolts straight to subframe
No mount for vibration dampers on the front end (non GTR)
±No HICAS
R32 camber arm has to be reused
Offset bushes are needed
I thought I would save time by buying a new subframe, prepare it and then just switch over a weekend, fooled myself again!