My tune..

[Halon]

I went to DB and had my timing around 20*, and I did not want to go any higher due to cylinder pressure.

We brought it down to 17* and hardly even saw a difference, so we left it at 17" as it's a "safer" level. You can run a ton of timing on E85 because it is just so damn knock resistant. But you have to be careful because too much can cause other issues.

I would say leave it where you are at, 19* is already a decent amount.

Just my .02 cents.