So I want to do an exhaust up grade but the wife said it has to sound stock, i have some good fab skills so this is what I was thinking. Put this in so I can run straight pipes or through a cherry bomb or some performance shorty exhaust when I drive and with the flip of a switch it can sound stock

 

I think this will be a lot easier, and sound a lot better:

SoundRacer V8 in a Mazda Miata / MX5 - YouTube

 

That isn't to difficult to do. You could achieve that two ways. One way would be with slip fits on the exhaust (which have a potential for leaking) or weld it in place. One thing you want to keep in mind with the exhaust cut out is that the shaft that has the butterfly valve on it does have potential for rust and seizing up.

 

That's awesome. Who would have thunk it?

 

Waldrons exhaust might have something for you. They make mufflers that have controls for volume by either rpm manual or electronic control. They make a great product. I use their exhaust on my fairlane and customer service is amazing. They are always open to helping a guy out.

 

Exhaust cut outs like that are illegal in some states. Just fyi.