Where can I find a muffler like this?

[aggressive male]

I saw on tv once that some GTO's came with mufflers that had a vacuum motor on them so when you open the throttle all the way the vacuum motor turned a baffle or something so it would be straight through exhaust. Anyone know where I can get something like this? You guys think this would be a good one to get?

[79TA01]

Don't know of anyone who is currently making those but I did see this post over on the Pontiac forum I frequent. Don't think they have the resources to mass produce them, he only made a few for himself and this GTO.
http://forums.performanceyears.com/forums/showthread.php?t=533408

[aggressive male]

Hey thanks! That's just what I was looking for! I'm also interested in other ways to do this if anyone knows. Wether it be some kind of exhaust valve before the muffler or one of those new mufflers that's actually a noise canceling speaker.

[HILROD]

I have installed a couple of sets of electric cutouts to do the same thing. While it's not automatic it can be loud or quiet. I still have a brand new set that I can't get to fit under my Camaro. With the X-pipe and it being so low, space is tight.

[aggressive male]

Are electric cutouts dependable?

[Project69]

Are electric cutouts dependable?

I wouldnt use those. The motors might burn out from the exhaust temp. and a few guys over at ls1tech say that they dont fully seal shut.

[HILROD]

The ones I've used have a 4 year warranty. The first set I installed had a slight leak from day one. The other two work flawlessly. They are not cheap, but either is this whole hobby! Also I've only run them downstream from the collector a ways so maybe that keeps them cooler.