Eisenmann Race break-in?

[brodiem]

I just purchased a new Eis Race rear section, and using it with deleted primary cats along with the rest of the OEM x-pipe.

I've tried to search but answers are totally contradictory depending on the person, so I thought I would ask...

I find this exhaust quite a bit more mild than I expected it to be. It replaced a Borla Atak, and the Atak is significantly louder overall. Up to around 3-3.5K it's comparable in volume, but 4k+, the Atak screams, while E. Race quiets down substantially.

So the questions I have are - any indications of how it might change during break-in? Many say exhausts deepen and become louder as excess packing material burns off, and many complain these are incredibly loud and full of drone, and then becomes milder as it breaks in. Which is it?

If I were to replace my OE X + test pipes with a Challenge Sport or something comparable, what can I expect will change over just test pipes? I'm not interested in going fully catless because of smell. I'm interested in making the upper RPM range more pronounced. I do like the overall sound signature of Eis , I just find it's kind of non-linear in output and it's the upper RPM ranges where it's nice for a Race exhaust to shine (otherwise I'd use a Sport exhaust). I'm hesitant to go and add an x-pipe without knowing whether to expect any amount of change with break-in and if a dual res+hfc pipe will change what I already have in any meaningful way.