[Christ]

One more thought - if you can get your hands on either "Delrin" or thermal plastic compounds, make a template from a normal intake manifold gasket (this only works for inline engines.) and cut it out of the delrin or thermal plastic. They're both natural insulators, which will keep intake temps down (debate on whether this is a good thing or not can be found all over the place on this forum), but they also can be used as "intake spacers" which will increase the EFFECTIVE intake runner length. (The length from the end of the "tube" to the intake valve head.) There are more gains to be seen here than by using a TB spacer in most cases.

Given a resonance chart, you can fine tune your intake runner length to provide the "harmonic bump" at exactly the RPM level you normally operate at, thus locating the KeyWest of BSFC right at that point. (I say this because it doesn't move the peak down, perse, but it does create another, smaller, peak.)

Harmonic bumps have extraordinary effects, since they cause a pressurized pulse to enter the engine for a VERY SHORT AND SPECIFIC duration. The higher your frequency, the shorter that period of time is.

If you google "intake Harmonics" you may find a calculator that will help you decide your optimum intake runner length.