Upon arrival Customer explained to me in his shower. There was a sewer smell upon inspection. Gave them option to perform smoke test on venting system. Also removed drain cover for shower and flushed 5 gallon bucket to flush P-trap of shower upon performing smoke test from roof vent, smoke emitted out out of every stack Indicating there are no cracks or problems with venting system. Also no smoke admitted in the bathroom or fireworks smell at this time no other problems arise.