Very nice!, you may use the Ha or OIII data on its own as a mask to create more dynamic range in the core to get more structures out. This one was a tough one for me and it was a lot of trial and error until I got something I was happy with.
I would like to bring out the outer halo more as well as the core. It is a bit too noisey when bringing out the outer halo for the amount of data have so that might have to wait until I get back up and running again. But I might play with the HA and OIII as masks or Lums to being out more core details. I am just surprised this much came out with no calib files at all.