sounds to me that you have been misinformed when you purchased your import. no turbo model skyline ever came out in 4 stud EVER, badges or not. in regards to your boost, did you install the ebc yourself or was it on the car when you got it. if it was on the car already then it could be the stock solenoid not being disconnected or bypassed thus not allow you to go over the standard boost level. if it was installed by a workshop, take it back and get them to rectify the issues. other then that, enjoy it.