Most of these have an "override" spring. If you watch the actual throttle lever on the side of the IP, once it hits the stop, the override spring allows you to pull a little further, but throttle on IP does not advance. Set so it just barely tensions the override.
No harm in going full throttle in neutral, it's called "hi idle" and should be around 3000rpm for a turbo 3208. No real point in doing that as long as you adjust things per above.