For jetting, I got a JD jetting kit, installed the jets for my altitude and then had to drop the needle one clip and it's perfect.
I go back and forth between the red and green spring but am changing to a gnarley pipe next week so everything could change.
Jetting a two stroke is not hard but it is necessary to take the time to study what you are doing, write everything down and try a bunch of things to see what works. I'm not super anal about it so I was really happy that the JD kit worked with only one small change.
If you can't tune out the violent surge with the jetting have someone dis-assemble your PV and check it out for worn parts.
The 300 can be tuned for an incredibly wide and smooth power band. Mine is unbelievably torquey, so I am putting a pipe on to see if I can get more!
