I took my car to Mustang Motorsport in Melbourne this morning to have a Roush axle back installed.
What an amazing place!
Mustangs of various vintages, Hellcats, Camaros, F150s, it's like muscle car Disneyland!
Excellent, very friendly service.
I drove in at 7:45 and rumbled out at 8:30, job done.
It's not too much louder, but it's definitely a deeper, throatier sound.
The sound when the starter is pushed is awesome.
At freeway speed, its barely noticeable from stock, but under acceleration there is a deep growl.
One thing that is really noticeable is the rumble when the auto changes down as its slowing under brakes.
The tips are 4 inches compared to the stock 3.5.
The extra half inch and thicker tip wall just seems to fill the space that much better, and the Roush logo embossed in the chrome looks the goods.
I paid $990 installed which I thought was pretty good value.
Installation looks pretty easy if you wanted to have a go yourself, there's a good youtube video by CJ Ponyparts showing how its done, though it might be awkward without a hoist.
I am very happy with the result.