There is a diverter valve or bypass valve build into the turbo on your car. It is electronically actuated. Adding an aftermarket one would be nearly impossible. Also there is a spacer available that will give you more sound. However it causes MAF over run and that will dump fuel.

If all you want is the sound then doing an intake like an Injen or the BMS intake with a cone filter will give you plenty of sucking and blowing sounds.