New engine question

So that is a normal thing? It sounded to me like it was coming from the manifolds so but the cylinders are right there and I was thinking it was compression passing the rings and it freaked me out thinking I did something wrong lol. With the plugs outs it don't do it. So I most definitely think it's compression related. This is my first ever engine build and im a nervous wreck over it haha.
Yeah man, don't sweat it. It is probably compression going out the exhaust as well.