First of all I am new to this site but have already learned a great deal about my 03 duramax I just purchased. I am curious about something. My father in law has a 01 Duramax and I noticed that I hear his turbo whine alot more than mine. I very rarely here mine whine even when I am pulling my fifth wheel. Is this normal. I have also noticed when I really step on the gas and the RPM's hit above 2,500 I start to here a hissing almost like a exaust or vacuum leak. I would also like to add that my father in laws truck seemed to have alot more power although it does have a cold air intake and magnaflow exaust. How can I test to see if my turbo is working properly?

check all your clamps on the intake tube and inter cooler piping

x2...also his is making louder turbo noise cause hes got an intake

I checked today and found a hole in my intercooler pipe. Took it to an aluminum welder and he fixed it. Fixed the problem. Thanks for your help.

x2...also his is making louder turbo noise cause hes got an intake

Exactly

intake and modded intake horn make the turbos way way way louder