turbo over charging
 

My 2008 Cayenne Turbo is having problems of lossing a little power and a overcharging of the turbos. The check engine light havent come on or any other light, We tought that the catalytic converters were failing because of the poor quality of the fuel here ( bolivia ) but hey are just good. Spark plugs new, and only 50 thousend kms.

What went wrong?