There used to be manual cut outs with a cable similiar to a choke cable. I haven't seen them around to much lately. Might check (OMG) jc whitney, Speedway or epay. Good luck!
Those "old fashioned - manually opened exhaust cutouts are still available.... and more than likely DO NOT work any better than they did "back in the day".
The also problem with them is they are made to "only fit" 2 1/4 exhaust tubing. With todays "standard" exhaust tubing being 2 1/2" or 3" they would not fit anyway.
Like Vall I also have a pair of "Badlanz electric cutouts" which I used for the temporary exhaust I had on the Opel when I was "sneaking out" and going to a few car cruises & shows (no head lights - brake lights - turn signals - Lexan windshield & most of all NO inspection sticker) .
When I get to fabbing an exhaust system I plan to somehow "hide" the cutouts under the car much better than I did for the "temporary exhaust" seup I had before. Another idea is not use the 2.5 electric cutouts at all and purchase the 5" ones that could be installed in the collector dump tube with an exhaust coming off a Y-pipe prior to the cutout???? Another one of "those I have to think more about this.
Another cheaper option for you could be having an old school "cutout" or a flange with a block off plate here in place with "tumb screws" which would make it "easy" to "uncap" and allow the exhaust to exit thru the collector instead of going thru the exhaust system/mufflers.