Excellent image of 253 Gary!
I assume that was the 6" F5.6? So only some 800mm FL? Some great details visible aaaaand I like your crop orientation, looks very familar
Not sure what you mean by remaining noise??? it looks pretty smooth to me..? Probably too smooth even? There are most likely some faint details and background galaxies lost in your smoothing process..?
Great work, you do some of the best DSLR deep sky work around
Mike