the car is knocking at low revs, and clearly feel lack of power. It still runs good and I guess the ecu has detected it and adjusted accordingly.

Any idea on how to drain it? Had about 4 gallons of 93 and he put 12 gallons of 87. I tried to siphon it but the pipe won't go far enough, also tried through fuel pump under the rear seat and that won't work either. I put in another 5.3 gallons of 93 so its probably close to 89 now.

What are the options? anyone faced similar situation?