Pertronix VaraFlow Mufflers

[696969]

Has anyone and any experience direct/indirect with these mufflers on a vintage car? I'm thinking of putting them on my small blocked '69 Satellite.
I like the idea of having em quieter when on the freeway or when I need em quiet and loud when I want em loud.

http://www.pertronix.com/prod/ex/varaflow/default.aspx

 

[krowbar]

You could do close to the same thing with electronic cutouts. With the cutout you can have it in front of your muffler and basically have open pipes or flow through your existing mufflers. Just depends on what you want it to sound like and how deep your pockets are.