i have the 04 wrx and i was wondering if i could find a small turbo but something bigger than the stock one and change without having to upgrade the fuel system and all. any suggestions?

 

You'll need supporting mods injectors fuel pump and all that to run another turbo. I'd suggest getting yourself a TBE and uppipe then getting any type of Engine Management and going Stage 2.

 

^ +1

 

It really won't be worth it for a slightly bigger turbo than stock. the power difference probably wouldn't even be noticable, let alone worth the money. You would get more bang for your buck with a stage 2 setup or something similar.