[zagrot]

CB has given you the key to the knowledge that you seek; helmholtz's work applies greatly to the design of an intake manifold, and to to exhaust design as well (though i'm still not sure if stock exhaust resonators are intended to attenuate noise or help exhaust flow). research "helmholtz resonator" and after a but of reading curtis' post will make even more sense to you. the major problem with intake and exhaust resonance is that the effect helps only in a narrow region of of the engines rpm. i once found a whitepaper on the design of an "active" helmholtz resonator which used a viberating diapharam in conjunction with a microphone in the resonator chamber, and controlled by an opamp, to cause the chamber to resonate outside of its tuned frequency. it is unfortunate that i lost the url, and i don't know if i downloaded the file; at least i printed a hard copy.