Though I can appreciate the look, why not just add some kind of racing type headers from your local automotive supply and drill a couple holes in the wood stove to mount the headers. Use a tap n die, mount some studs and bolt it on. Even have a custom bent exhaust pipe to whatever configuration you'd want.
I think the heat would transfer from the stove to the headers and pipes making things heat a lot more efficiently. Or not. You could even find an old intake manifold with an empty carburetor mounted on top to make it resemble an engine. Not that it would make the wood stove work any better, but it would make a heck of a conversation piece instead of spending mondo bucks on something prefab, that likely wouldn't work much better than the typical wood stove especially if it were EPA rated.
Anyway, it's a thought!