The stock is 2 inches however buying a cat back would be more for looks and sound. It's damn hard to find a full exhaust for the car because the exhaust system is soo complex from the original extraxtors, and you cant mess with it too much. The extractos are another hard item to find, if anyone does find one apart from the trd which is alot of money, please let me know. I wish more aussie shops were into tuning toyota's so they can make parts here, bloody hell, its always nissans. scoobys and hondas.