btw I dont completely understand the GTP name tag. wait 7 weeks after doing a time trial?
The GTP_PSN ID name tag is required to complete the GTPlanet Weekly Race Series (WRS) Qualifier Time Trial and to race in the WRS but isn't required for casual online racing on GT5. Once you are happy with your WRS Qualifier time and have submitted it you will get a PM in approx 7 days confirming which division you're in.
The benefit of creating a GTP_PSN ID and completing the WRS Qualifier is to identify yourself as a GTPlanet member to other online racers and grade your ability against other members. If you do create a GTP_PSN ID you are expected to abide by the GTPlanet OnLine Racing (OLR) Rules & Guidelines, this and other info is in the links below.
GTP_Registry & Qualifying Race (GT5P)
GTP_WRS Divisions (GT5P)
GTPlanet OnLine Racing (OLR) Rules & Guidelines