never retard timing to allow you to run more boost
run as much timing as possible on a safe boost level - ie dont run scramble boost, boost switches, dual boost, stage boost, just run one big single safe value then tune - never adjust boost while tuning either. set it at the desired level and lock the controller away. dont EVER run most boost that what you have tuned for. thats how engines fail
the more timing everywhere the more crisp and sharp the car is on throttle
the less timing you run the more sluggish the car is