Don't know if it's been posted before, but you can:
- Use a Z32 fuel filter
- Use CA18DE Intake Cam for some more torgue
Edit:
Cheap/Easy upgrade:
- You can use the FMIC from a Volvo 740 Turbo, or a Saab 9000 2.4 Turbo instead of the standard WMIC.
Oh btw,
I Live in the netherlands, and all S13's here come with CA18DET Standard, so if you guys have any questions at all don't hesitate to pm me!
I'll browse thru the FAQ tomorrow and if there's anything missing i'll post it here