Depends on the tips. For the most part, I'd say no. The '65/'66 GT tips with louvers, though, definately change the sound. When I had them on my last '66 coupe, it sounded much quieter with the tips on, and kinda baffled from the louvers.
If you always do what you've always done,
You'll always get what you've always got
If you always do what you've always done,
You'll always get what you've always got