I had the same issue, as soon as I tanked up in NY I had knock anytime I got into boost. I checked things out and nothing was off. I talked with Yusuf Begic(own of the LHD Evo 2), he suggested to drop in a gallon or 2 of E85 with a full tank. I did that and back to zero knock. After I burned that tank up on the way home and refilled at Angola, knock came back.

I brought back 5 gallons of E85 to play with, hell it was only $15 lol.