How to lower noise emission?

Hi,
Before going on track, bikes should pass a noise emission test at 5000rpm, not on roller, only in static. Limit is 99dB. Easy for I4, but hard for V2 with open exhausts, even with dB-killer.
Is there any chance to lower noise, 1, 2 or more dB, playing with ignition advance and/or fuel mapping ?
If yes, which direction should I try ?
This will be implemented in a "test map", which will not be used on track
So I don't care about driveability, heat,....The test will last only fiew seconds.
Angelo
Before going on track, bikes should pass a noise emission test at 5000rpm, not on roller, only in static. Limit is 99dB. Easy for I4, but hard for V2 with open exhausts, even with dB-killer.
Is there any chance to lower noise, 1, 2 or more dB, playing with ignition advance and/or fuel mapping ?
If yes, which direction should I try ?
This will be implemented in a "test map", which will not be used on track


Angelo