I know this is going to sound really vauge, but I was walking the other day and a Mach1 pulled up to a stop light next to me. That thing sounded Awesome!!!! There was no way to tell if it was aftermarket exhaust or not, but it sounded better than any car I've ever heared....And I have been around. So, is the Mach1 the best sounding car ever, or did the guy pull a fast one on me and make it sound like that....Cause that thing was sweet..

 

exhaust mods are extremely easy to have done, if he caught your attention that much I'd say it was aftermarket, though the stock mach 1 exhuast sounds awesome. Also that would be one of the last things to do on a Mach 1 it already has a great aftermarket look to it.

edit: also im pretty sure a stock Mach 1 just has the rounded exhaust tips.

 

The Mach 1's came from Ford with a good exhaust, they were different than the GT mufflers and quite deeper in sound. The tips are rolled chrome ones also. I won't even be changing mine out they are that good as is. Combine that with the music of a 32V DOHC V8 and you got a winner.

 

I have an exhaust clip of mine I'll have to post tonight.