What fuel should I run: 91, 93, or can I use 87?

This one comes up constantly because gas station options vary by region. Subaru’s published WRX specs list premium unleaded, 91 octane or higher. In owner discussions, the consensus is that 91 is the minimum target, while 93 is preferred if it is locally available and priced reasonably. Community comments commonly describe 93 as offering a little more knock margin and sometimes slightly better behavior, but nobody treats it like a magical huge power gain on a stock tune. The practical owner answer is: run 91+ consistently, avoid cheap questionable fuel, and use the best premium you can buy conveniently.