Addon silencer for performance muffler

[Brainless]

I have a new exhaust system but it's a little to loud on the highway and I'm afraid it could give headache on longer trip. The muffler I have is a 2 tips brospeed prosport muffler and I wanna know if there's a way to add a silencer to it (only for long trip) even if it could result in a lost of power.<P>thanx!