I looked into a set of these last summer as an alternative to the problematic supplier I was using for a Jenveys/ECU package.
Very clued up sales staff, they offer a good package with the Typhoon ECU as well which is good.
The location of the butterfly/barrel in relation to the inlet port division isn't so critical as opposed to the overall inlet length compared to the engine speed window. For rarefaction to occur and give optimum power the overall inlet length (back of the inlet valve to the bellmouth) needs to be around 330mm with a 7500rpm peak power target. Bellmouth diameter needs to be chosen to give a target airspeed of Mach 0.5 too.
hogdog - drop me a PM if you need any more info
