Te chip is mapped for 91+ Octane. This is the first chip i installed in my car shortly after buying it. After getting the header and full exhaust, i replaced the Promax chip with RS barn's stage 2 chip designed to work with the header/exhaust. Now i'm on my 4th chip (which is a custom map made for my car, had it dyno tuned). The Promax chip has been sitting in my house for 2.5+years unused.