Same way one checks for any exhaust leak; block the exhaust pipe and scan joints for leaks.

A vacuum leak would cause a code and performance issues.

Have you investigated the various bearings and belts? Alternator, A/C, idler etc.

A $5 stethoscope would be handy.

 

Yeah checked all those and took it in to my uncle who owns a shop, we couldn't find a leak anywhere. He thinks I am probably just overanalyzing engine sounds.

If what I am hearing starts to become more noticeable then I should be worried.