Use E85, put 2-3gal in a tankfull of 92 and you will get 93+oct. you only have one Gas station that sells E85:
Bob's Automotive & Gas
Phone 503-788-0545
9694 SE 82nd Avenue
Portland, OR 97266
Business Hours 5:30am-11pm daily
Payment Methods Cash AmericanExpress Discover MasterCard VISA
This is by far the cheapest way to boost your octane.
John