my biggest power adders have been this
GMS 65,000 volt coil packs
JBA shorty headers
Tune via henson performance. 93 octane.
the exhaust + K&N
75mm throttle body
GMS Shark plenum + polish
Professional products manfild + polish.
the 75mm gives no more advantage than the 70 unless your going to run cams or forced induction. You would be wasting an extra 120 bucks that you didnt have to.