I had BC coils dropped to 30mm and ARK exhaust on the 370z when I bought it. I left half of the exhaust in Wales, you can still see the scrapes on the tarmac in Evo triangle, Devils bridge etc
Start with 20mm and go from there. In case you need to adjust rear camber, the arms are not very expensive, only about £159 for the rear camber arms from what I remember. See how they feel, let them settle for a few days driving and report here