I have a Procircuit graphite front pipe and an RSV aluminium tailpipe. The baffle in the tailpipe can be removed- its a straight-through perforated tube with rockwool wadding around the outside.
Is the wadding just for reducing the sound levels, or does it actually help produce back-pressure to aid the engine?? I removed the wadding, as it was all oily and gummy. Will it damage the engine performance if the wadding isn't replaced?

Nick

Removing the wadding makes the exhaust much louder and reduces engine performance (aso can dangerously effct jetting). Once the wadding gets gummed up and oily it needs replacing. MX dealers will hold stocks of replacement wadding.