^^^This!^^^
To the OP, sorry I did not get to read through all posts, and I have a ton of experience with E85 on boosted 3sgte's, NOT the UZ platform. So take the following for what its worth.
My personal MR2 is currently running pump E85 (last test was E75) at 43-49psi PTE6266, 766 HP 698FT/LB TQ. I have an MLS HG, and ARP L-19 head studs. And this is just a 4 cylinder, camry block, 3s head.
So what im saying is E85 is not an invitation to just keep running in timing, but it does absolutely love more boost, provided your fuel system can supply it. I also suspect your ignition issues are due to being too rich, for example on a gasoline AFR scale i'll run 12.5-8:1 under boost on e85. It IS the only engine I have seen that likes it that lean. In the low 11:1 range it will have ignition issues, lean it out and they go away.