I bought a 06 wrx, I'm new to modding and all that.
I'm interested in buying from Cobb their stage 2 power package but I read on their website "For use on North American ECU only".
My car is made from Japan, (VIN starts with JF1).
Will it work or should I consider another mod to add few horsepower

You might want to ask on the cobb forums, but since they are rather explicit in the notes that it is for USDM ECU only, I would bet that it is an actual compatibility issue to non USDM vehicles.

However, if you purchased your vehicle from a dealer here in the US, then I bet that you in fact have a USDM vehicle and ECU. The only way to JDM AFAIK is crated cars and conversion jobs.

-edit-

Hmm... Tahiti... so you probably DONT have USDM vehicle...

Thank you, I will try their forum.:)