At least, I was told by Mr. Clubine that it is an exhaust for a 93/94 Van Diemen. I'm happy to take any measurements anyone needs to confirm it's suitability for your use.
Anti-reversion chambers and one small (apparently well-executed) patch on the upper section of the "2" pipe portion.
With a port for an A/F sensor.
$500USD (plus shipping, naturally).