Borla Touring and FRPP Touring pretty much the same and as far as I have heard the quietest of the aftermarkets.
Deep at idle and under 3000rpm but some growl when you get on it. Some resonance on the highway at low rpms in 5th and 6th, like 1700-2000rpm, have to stay higher rpm's to be quieter.
Roushs I have heard kind of raspy.
Ain't going to sound like a V8 but sounds decent, its too quiet stock!
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