Rattle while backfire

[Ern_1000rr]

Hi all! Quick question. I noticed funny thing- when I ride slow on low revs while backfire can hear rattle on right hand side of Engine and like under tank. It?s quite annoying also got feeling like vibrations are stronger on rear sets and handlebars. Exhaust full akra moto gp, flashed bike has 4300 miles. 2018 model. Basically engine sounds ok, idling ok, just while ride; close throttle, backfire and rattle ?*???*???*?? Checked all fairings and headers and looks ok. Can has loose rivets but don?t think it?s causing problem. Any thoughts?
Thanks