bolt ons:

headers/ported manifolds and downpipe
ported throttle body
ported blower
intake (make your own)
thermostat (180* instead of 195*)
plugs (colder than stock)

kind of bolt ons:

rockers
pulleys


dont even THINK about a pulley unless you have a considerable amount of mods. the series III needs more mods than a series II in order to drop pulleys.