cant fit much else, need at least 17" to get some decent room.
typical option woul dbe to use supra twin turbo DISCS with your stock calipers or Lexus IS calipers
but you just remember that you need to make an adapter.
so:
$200-300 for ann adapter
$200 for discs
$no fkn idea how much calipers cost
if you want 'bigger brakes' erm... WHY?!?!?!?!
if you want better braking power/feel
start by:
bleeding all 4 brake lines
replacing pads with some hi performance street pads
get new discs (plain blank bremo discs are cheap)
replace rubber lines with steel ones...
but remember it comes down to your tyres to actaully STOP the car