With loud, drony exhausts I've found that its all about gear selection...my exhaust drones like a bitch at 2000rpm but is quiet as a mouse at 3000 then absolutely roars at 4000 and above...so you basically have to compromise fuel economy to keep the noise out of the cabin with the louder pipes
And mine peaks at 120db and my hearing is fine...as long as you speak very loudly...
