I owned several newer Mustangs in the last 15 years. I had a 12 model that had Pypes muffler eliminator tail pipes installed by the original owner. It basically just ran the cats as mufflers. Apparently Pypes did some tuning with them but I’m not sure how. They were fairly loud but fairly deep and not raspy. I actually liked them a lot when rowing through the gears.
Then I bought a slightly used 17 Shelby GT350 Mustang with the dual-tone, anctive exhaust systems. For some strange reason it was set up to open the valves in the mufflers when you park it. The first morning I went out at 0630 to start it and it kicked off with an enormous blast that would wake the dead for 3 or 4 seconds until the valves would close. That first morning my neighbors Great Dane that was in the back yard was so startled, it raced back into the house, into their bedroom and jumped into their bed. This was never going to do so I started researching how to work around this open muffler start up defaults. Strange that Ford didn’t provide for this. I finally on my own found that if I left the clutch pedal alone and pressed the start button, it would power up the muffler valves and close them and after a couple seconds I could then press the clutch down and hit the start button, which still let it start with a rumble but much, much less like an explosion. I got to where I would typically drive to work with the active exhaust systems closed for some relative quiet. But coming home from work I would frequently open it up to listen to the system when rowing through the gears. With the flat crank and different firing order it had a different sound than normal Mustang GTs, probably less raspy but definitely a loud shriek on its way to 8,000 rpm’s. Sold that after a couple of years but I do miss driving it.
A couple of years ago a neighbor kid got a new Mustang GTs and he replaced the active exhaust with something. It’s even louder than the Shelby was when he fires it off in the morning. I was out jogging one morning and could hear it plainly several blocks away. After about a minute of warmup it settles down to a rumble but then he climbs in and rips it through the first couple gears leaving the neighborhood with a raspy shriek and howl from the exhaust. Drives the neighbors crazy - I call it the Mustang from hell. How’s that sound for an old, grumpy man deprived of his hot rod Mustang? Fortunately he has gone off to school or moved out of the house and all is peaceful - except when I fire up my 66 Vette with the side exhaust, 12:1 compression and 256/266 solid cam.
