The wastegate does a couple things. The main thing it does is it will vent of release some of the exhaust past your turbo so you do not overspin it and also keeps your boost levels down. It also keeps your drive pressures down (the pressure in you exhaust between your turbo and motor.

 

what he said,

the star wheel adjusting like you are doing is perfect, just move it a little bit at a time till you find the sweet spot. depending on if your motor was a CA emissions or a Fed. emissions truck the tuning can be different between the 2. i would un-tie the wastegate and keep adjusting the starwheel until you are happy. that will make it better in low-no boost situations.