Check to make sure the bolt that holds the alternator is tight if i remember its pretty long and rattles if its loose and wont be visibly obvious. Also check the hood, long shot but if the insulation is not on there or if you have breather hoses from the valve cover sometimes that can cause vibrations or at least make some noise.

 

i have rubber hoses from valve cover to catch can, alternator is tight, pulleys are tight. I tried even taking off the belt see if anything changed and nothing

 

Any update on this?

 

In for updates as well. My car had a pretty wicked vibration at about 3k rpm that goes away shortly after. Wondering what the resolution was.

 

It happens with turbo cars. Was posted about earlier in this thread. Brace the stuff and the vibration will lessen but not disappear. Shouldn't be horrible though. If so might be something else.