They will break in and get a little quieter at cruising. I felt the same way at first was annoyed on the highway. After 1000 or so miles quieted down.
I have have a stick with 2.73 gears and found it is louder in 5th and 6th at low rpm's around 2000, if you avoid the bad resonance rpm they are quiet even under load on the highway.
So what I try to do if I am on the highway with some traffic I don't let it get under 2500 rpm.
Now: 2016 Mustang GT Fastback-Magnetic Metallic, Ford Racing Touring axle-backs, Ford Racing front strut and k-brace, K&N CAI, sound tube delete, 1975 Corvette Coupe-L48, 4-speed
Past Lives: 2001 Corvette Z51 Coupe, 2012 Mustang Grabber Blue Coupe, 2008 Mustang Torch Red Vert, 1988 Mazda RX-7 Vert, 1985 Nissan 300ZX, 1979 Mazda RX-7, 1971 Datsun 240Z, 1972 Fiat 124 Vert, 1971 Chevelle, 1970 Challenger