Need? Or want? I would guess your vehicle rolls down the road right now just fine, therefore you do not
need anything.
Anything else you should get for what exact purposes?
Off the top of my head, with the limited information you provided, the following items are not expensive and would be logical addtions to your set-up.
Proper wheels and sticky tires.
Whiteline or Superpro caster bushings.
IKEA brace.
Everything else you could want is listed right here:
http://www.sr20forum.com/driveline-t...formation.html