whick system to purchase? 04 civic si any suggestions,

 

You'll need a wet kit (unless you go with
Hondata's K-Pro, a user customizeable ECU
or some other ECU/piggy back solution), keep
that in mind.

Sorry, I don't know enough to recommend a
specific brand or kit, really.

 

wet NITROUS EXPRESS NX ALL THE WAY

 

boost in a bottle!