typically they rattle when loose and when they are tight it's a funky exhaust note as maybe not closing all the way, have them checked if they haven't been or are in question..
not too complicated to check, a lil more involved to actually replace shims for adjusting, easily doable with tank off so forth, the valve hold tool is nice to have tho.. a little math and its on, service manual walks you through it, worth doing to know where you are here.. then a throttle body sync..