i have a blitz nur spec exhaust that comes with a silencer.
when i had it dyno'd i got 193kw,then i put on the silencer that came with it and only lost 3 kw,i got 190kw with it ON.
So i think 3kw is not that bad of a restriction considering it silenced it a fair bit,and would be able to cruise around without the worry of getting defected.
So i think a loss of 3kw is worth not having the hassle on the streets,and just rip it out on a group cruise/e.creek/dyno's ect.