Tuning Ignition for Burble Effect

Hello!

Car: 2016 Subaru WRX | Platform: FA20DIT

If a tuner wants to achieve a popping effect on up-shifts and a burble effect on deceleration, how does an already optimized ignition map need to be manipulated? I'm guessing the minimum load values need to be decreased within the desired RPM range but how much ignition retard is safe at closed throttle?

For example, my current ignition map is fairly optimized for my modifications - running about 28-33 degrees of ignition advance from 2,000 to 6,000 RPM at minimum load. If I wanted to achieve this popping effect within this RPM range, what changes would I need to make to the minimum load column?

Thank you!

clint i often run as low as -30 deg in this area (warning added make sure your valve train is up to the task )