So yesterday I was reading through the whole https://www.v1engineering.com/forum/topic/laser-engraving-not-really-getting-great-results/page/6/ applied the changes in Marlin.cpp and I was good to go.
First picture is a simple bitmap which I aborted yesterday and then did again today with much better results after the change.
Then I went to Davids G-code file, for the Garfield, that file is firing the laser up to 100%, so was not really working for me -LoL. Results on the right 
I used then the jpeg image and did my own G-code file. 40% 50mm/s resolution in width 0.15mm, height 0.17mm. I could notice the X-axis slowing down, but overall not a bad result for one of the first trials.
Thanks again everybody for their help.
