[thumbster]

Originally Posted by bjowett

The box has a huge flap on the side which opens under higher throttle/higher rpm operation... pretty much the same as cutting that big hole, but resonance and sound are kept stock for lower rpm.... neat stuff.

I was thinking about the vacuum actuated door idea, but I didn't want to risk not getting the whole experiment done, so I just took the brutal approach. I guess you could take something like a vacuum advance unit from an old V8 distributor and make it work that way.