Nice, image with some really good data.

Processing looks okay but like Rick stated you will need to do some clever combinations to keep the core.
To bring out some really nice detail in M42 you need at least a good 2 hours of data, then you wont have to stretch and cook the image. (Processing will never compensate for a lack of good data if it isn't there it isn't there, this is a very time consuming hobby)
You really need to post your image info so people can assist better, exposure time, number of lights, did you have darks and flats, ISO, camera and scope may also help.
Carl