He will be emitting the most noise from the intake if hes got a 20 valve. The funny thing is, they do static tests at 5k rpm. My motor sort of has a quiet spot at 5k, but its loud as 4500-4800, so hopefully he is the same. Does he run a cat, charcoal canister and purge solenoid? You can control purge with the ecu quite easily.
If he does the above the only thing I can see him getting pinged for is the static noise.