Break in period is bogus.
Run a heat cycle in gear. Rolling starts. No launching. 30-50 miles. Be nice to it.
Let cool over night.
Then hammer down rolling starts again. Don't hammer from stop. Use paddle shifters and very rpm high and low shifting.
Anyone in the racing world knows you don't baby the engine or drive train. Drive it hard. Seat the rings.
Change the oil at the 501 mark.
Just hit the 501 mark today on mine.
Changed everything but transmission fluid today.
Diffs looks pretty clean other than black from heat cycle. Tcase was clean. Engine oil was pretty dirty.
Been driving hard from day 2 after heat cycle on gears.
If break in really matters why does Chevy put a brand new corvette on the dyno after the build line. Hard pull bouncing off Rev limiter. I've been to the factory and seen this is person.
Hellcat motor is a race motor. Build for power not babied.

I would also like to add you don't get full power till you hit 501 miles.
I saw on average 450-525 horse power.
At 501 hard pull it showed 698 horse power.
Havnt used launch mode yet.