I get the idea of acoustic balance in chambers, resonant frequencies, standing waves, etc. This reminds me of tuning a 2-stroke motorcycle exhaust system. The very nature of that system needed restriction on the aft side of an expansion chamber to effectively find a balance whereby the exhaust system worked like a pump, using the shock wave to evacuate exhaust from the cylinder at the right moment. All very carefully timed. Found in my case by trial and error. If you don't tune this right you pull out too much of the next cycle's atomized mix... and less power. Tune it right and whop! you get a kick a in the pants (in the "power band") and that little engine just "grew" three times bigger, so it seemed. Back pressure can be a good thing. I can easily see how this translates to fluids echoing around in a hard pipes. What I can't see is how negative peer pressure helps forums like this.

__________________
Cheers!
Scott McPhee

1987 300D