Full exhaust would definitely be your starting point mate.If its too loud, piss the redback muffler off or put in silencers. i wouldnt be touching cams unless you can change the computer int hese, they dont like it too much.
rule for NA is:
filter
exhaust
cams + ecu
throttle body port-matched
inlet manifold portmatched
port on the head
thats it mate, oh and fuel pumps etc to handle. so, your next step is exhaust-just do it already!