Most people dont mod their 4afe's for power. You could go with some suspension mods such as springs, sway bars, strut brace which would make your car much more enjoyable.
for $1000 you could find a nice reco ge and gear box, maybe even a half cut for $12-1400.
Then save a bit more for installation and rewiring.
should be able to do it for $2k
Any other mods on the 4afe are almost a waste.
But...
- extractors?
- full exhaust?