Here is a hard to read table of mine, I was running by Scottie-GNZ's rule of thumb. Get all timing in by 3000 and then drop 1-1.5degree per psi. Helix timing is lower for sure under boost. At 3K and 160kpa I'm at 26 degrees, he is at 23. Helix 14 degrees at 4500 and I'm at 24 degrees. I didn't have any pinging on 91 octane, but higher altitude. I thought at the higher rpms like 5k, 6k the engine wouldn't be loaded as much so more timing could be run? Mine was stock turbo engine running 14psi max,even though the table goes higher t3/t4 with npr IC and 12:1 AFR under boost(more like 11:1 right when boost first hit).
EDIT: 14psi at my altitude gave me about 14psi+11psi=25psi manifold pressure, 25/.145=172kpa
So I only ran up to 172kpa in my table
MAP
220-5-20-18-18-18-19-19-19
180-5-20-18-20-20-24-24-24
140-5-20-20-22-26-30-30-30
100-5-20-26-30-34-38-38-38
90-5-20-26-30-34-38-38-38
70-5-20-26-32-36-39-39-39
50-5-20-26-32-36-40-40-40
30-5-20-26-30-34-38-39-39
rpm.4-.6-1.5-2-2.5-3-4---5
rpm in k