Grinding noise/feeling around 6000rpm

[Dead Eye]

I wouldn't rule out the chain and sprockets due to handlebar vibrations. I just fitted a new front sprocket which has gotten rid of the knock I had (through left footpeg) - I knew this was definitely the reason. But after my test ride, I found the whole bike to be a bit smoother and it was vibrating less around the handlebars as well

In any case, if its engine based then it will have nothing to do with road speed which pretty much rules out brakes, chain, sprockets, wheels etc etc - need to focus more on the block imo