Surprisingly my SLP Loudmouths are very tame at idle, can't hear them over the Mach 460 on the highway, but will scream when you bury the go fast pedal. Of course at the moment I still have cats. I did notice my flow 10's and flow 40's droned something fierce on the highway in my last Mustang with no cats. Couldn't hold a conversation.
It's just one of those things where you will have a clear divide on taste.
I love the smooth mellow sound of the Magnaflows, but can't stand an off-road xpipe setup as it's just offensive to my ears.
OP add a Mac Prochamber in there and you'll love the beautiful music your stang will make. Flowmasters pair very well with the Prochamber.
All that said, nice car!
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