they arent a performance enhancer, they simply "retune" the unideal manifold length versus port opening time, when circumstances prevent using the correct length manifold for that rpm...
"fill in" the flatspots. sand back the high spots...smooth it all out. when installed correctly.
(unless, in the few cases, where everything is tuned to peak at the same time for max power at one speed only)
could see them as a cap in a filter circuit, could see them as a water hammer arrestor...
what diameter bottle, what length, internal volume, length of connector, size of connector, exact spot that connector is inserted into manifold, port timing, manifold length, crankcase volume...
hows about a telescopic inlet manifold?