The problem is in the part between the two turbos, the part looks like a "mushroom" with a spring and it is inside the tube between turbos. Spring on the "mushroom" is not tense, it has loosened a little and that makes the rattling sound. You need to replace that part, a good mechanic can even fix it without replacing part.
![](https://s2.save4k.ru/pic/FrtuTFcejLs/mqdefault.jpg)