That is the XS 7900 on my signature
Out of the box Stihl square skip doesn't cut very good, that's what I used on the 32" bar, and I was really leaning hard on it. I remember using out of the box RS chain on a stock 661, and it was so grabby it was hardly usable. Either the saw would jam to a stop or it would always try to climb out of the cut. Anyway, I was going to start with a noodle cut on the big log, but it just sat there screaming like the chain was dull, so onto the cross cuts.
Here's a 550 with just a muffler mod running 24" 3/8 full comp, not bad for 50cc and no porting.
https://img.masterblasterhome.com/data/video/107/107903-b1b7da852d16c1d9a1a6e96056de6f04.mp4