first we get suckered into a "break in procedure" discussion and that must have gone well enough to bring us into jetting. whats next, politics and religion.

Lets assume it had perfect jetting to start (big ass-umption), and now you have some sort of exhaust that is flowing better and you think its more lean. I would go up 2 or 4 on the main (like 164/165 instead of 160 etc), and raise the needle (drop clip) 1 spot. Go safe and fat, then lean down from there as needed based on the spoog/plug readings. and feel. Just a pipe change should be hardly any jetting change, unless the mix was way off to start. On my ktm oil burners, its surprising how much leaner lots of folks run them compared to the manuals jetting chart. I do need to compensate when running highly oxygenated fuels like the sunoco 104 or vp u4.

I like the ideas of cleaning the carb and powervalve first, and starting with brand new fuel, mixed with either motul or belray HR1 oil first. Start with the basics before chasing the jetting. maybe check for air leaks too at the carb boots before changing brass...