Ok, so im looking into doing a couple small mods on the G, and i wanted to start with air flow...what im wondering is, can i use the Stillen CAI with the High flow air box? Also, which is better, the injen CAI or the Stillen CAI. Thanks!

The stillen CAI is a "high flow airbox." It uses the stock g35 intake pipe. You can upgrade the intake pipe with a 350Z tube instead for added performance. Do a search on this topic since it has been covered thoroughly.