Hi...
Thanks for writing... and sorry I have been away from RCU a bit....
No reason, technically, that the Jett-Stream would not work with the diesel. However there is a difference in how the fuel is used, how it flows, and the temperatures involved.
I have not personally done any testing or research on the tuned exhaust on diesel engine. But as you said.. diesel is a slighty "slower" process.
If the engine would indeed run at 15,000-17,000 rpm --- then you should get some boost from the tuned exhaust system.
MANY years ago I did play around with the OS28H engines on diesel. We were running those in small Crickets and for a brief time on a Kalt Baron (helicopters). The engines ran well, good power, and were particularly good in midrange.
Im sorry I can provide much more info -- but please, if you experiment -- feel free to post what you find back here
Bob