Sway bars (adjustable)
Anti-lift kit
Roll centre kit
Proper Alignment
PERRIN, Whiteline, Cusco, take your pick and smile
All that under-body bracing only really necessary if you are chasing lap times/competing in some weekend event, as russ said, it will make the car too stiff for our roads.
Can do springs/coilovers later on depending on what you want to use the car for but those starting mods will make a noticeable difference.