Borla 08-14 Subaru STi / 11-14 WRX Catback ExhaustBorla(r) Performance offers a quad exit Cat Back(tm) exhaust for the venerable 2008 2014 Subaru WRX STI. This race inspired system (PN140312) checks all the boxes on every Subaru enthusiasts hit list, taking this flagship to an even higher realm, of performance. For starters, Borla(r) engineers upgraded the Stir's exhaust plumbing from 2. 5" to 3" in diameter. The resulting increased airflow through the turbocharged powerplant provides horsepower