5.2 magnum GT35 to S475

What “they” say is correct. Peak torque will always fall right at peak VE. So you pull an additional 3 degrees, in how much of the map? On traction limited stuff, (street tire) I usually keep the timing out of it down low all the way to peak torque and ramp it back when the tire has less chance to break loose. AEM infinity has tables that can be referenced to speed or gear. Boost by gear or boost by speed are two of my favorite tuning tables.
I pull the most timing at 4k and ramp the timing out starting at 3750 and put the timing back in at 4250. On street tires I’ve been using timing retards using boost vs time and it’s worked out well so far.