Getting new turbos is easier said then done. The noice is probably comming from your wastegate actuator starting to go bad,if so they won't replace the turbos unless the wastegate goes bad and starts effecting the trubos themselfes. In the case of loosing boost, check your chargepipe for cracks or leaks wouldn't be bad idea to get an aftermarket one. If you get the jb4 g5 you can control that noise much better
good luck.