when you're busy with problem cars eating into others time on a busy dyno id say.. you go drop your own exhaust book it in for another runup if the problems gone then there is your answer..
2 bolts and a 5 min job, on a hot exhaust? yeah nah you would have to let that cool which is time, unstrap and take it off the dyno more time, put it back on the dyno yet more time, get it back to running temps YEP you guessed it more time
if I was getting something done and they said "this is a problem holding you back from your best possible results" well then id fkn change it regarless especially with something as important as an exhaust