ColinAnder67555STi

Can anyone give me some advice on a overheating issue. My 2006 STi is overheating when idling and stuck in traffic, and also when i drive it hard. There are no leaks and its had all new coolant pipes and new thermostat, coolant header tank and overflow bottle. I have been told that this is a common problem with STi's from this era. The overflow bottle fills up when ever i take it on a medium/Long run. Any Advice would be greatly appreciated. Thanks