strange noise

I changed the header and removed the Ais. Since the powerbomb is installed, it seemed that the engine jingle a bit more than before. I have torque the header with 20Nm (like my dealer said). Everything seem O.K.: no gases come out- but there is this strange noise. Sounds like an iron small ball is in the header- but there is nothing.

Is it normal that the enginejingle seems louder with the pb header?

Act. have about 15.000miles not the time to check the valves or the timingchain!?