Which turbo do you have.......compare airflow numbers to what your turbo is rated at......

small 16g = 34lb/min
Big 16g = 36lb/min
Evo 16g = 44lb/min

With the right combination of mods, you can achieve these flow rates. General ways to increase airflow include turning up the boost, cams, portwork/headwork on the head(this depends on turbo itself) and Sheet Metal Intake Manifold. That is not in any kind of order by the way.