Jetting after squish set

[Cox76y]

Im currently running 175 main, 42 pilot with NECW on 3rd clip and believe that my bike is still running rich. Air screw is 1.5 turns out. Im getting what I think is pipe bang when coming off throttle. When I come off throttle there is a second or so when the engine gives a ting ting rather than immediately settling into a consistent idle. My 2012 model with JD jetting didnt do this.

Everywhere else it seems fine apart from there being spooge coming out of exhaust. Plug is pretty black too.
Just wondering if getting the squish set means that I will be running leaner than I would if the squish hadnt been set. Im thinking of going to the NECJ needle and giving that a try.
Bike is a 2018 ec300 and using the chart supplied by gasgas Australia my bike should already be running lean with these settings.
What is everyones opinion, would dropping the main to a 172 be a better option? Should I try a 40 pilot??
thanks

JC