The issue of ratios for skyline diffs has been addressed with various ratios avilable the std for a gtst,gts4 is 4:3( though the gts4 is a vicous diff the same size as a gtr.) ,gtr and is 4:1 and some silvias have 4:1 and 3:7 available i have 4:1 gtr centre also with a little tricky fabrication a 3:7 300 zx centre could be fitted which is bigger and stronger than a gtr centre .
so as you can see ratio's are not realy a problem.
I have 2 x 300zx 3:7 centres a 4:3 gts4 and a sil 4:1 which i think is sold . there is also a range of sway bars you can get from 15 mm to 30 mm hollow.
hope this helps your decision they are a good kit that is fairly easy to build and light mine came in at 1042 kgs with a roll cage and tools also 1/2 tank of gas.
