Muffler Testing, etc.

I have a QuickTime electric cutout on my Dodge Ram. It uses a electric motor to open and close the cutout. Looks like a choke plate on a carb. I like those mufflers your have because they sound like they seal better. The cutout used to seal really well when new but I got a very little "hiss" that I can hear now when closed. Most say it needs cleaning but I haven't looked at it.