Hey guys,
Here i am (yet again) with a problem to be identified.
This sound is most noticeable when the engine is cold started and after i've driven it a fair bit it goes away. Idle when warm is smooth, however i have got a boost leak (just additional info here), my electrical boost gauge is showing 5 psi. Alternator belt seems fairly loose when pulled (maybe one size too big).

Standard 13btt with cat removed and fmic.

Thanks in advance.

 

bad alternator bearing or idler pulley bearing..that is what it sounds like to me.

 

^-- what he said