What is the original turbo of 2006 sti? Is it better than vf34?

 

A VF43. The VF34 is probably the slightly "better" turbo although I've not heard of one fitted to a 2.5 engine yet.
The VF43 still needs porting despite its bigger wastegate as it creeps on a good exhaust. - not sure if the VF34 also needs extra work.
Nick

 

if its a version 9 isn't that stil 2ltr, 2.5 were version 10 , i could be wrong so don't take my word for it