Hi Claudio,I was very interested in your thread. I know a guy who played with a 6cyl motor on a dyno and claimed that there was no noticeable difference when he manually operated the low speed/high speed intake manifold internal baffle diversion plate. I am not surprised either way, seems to make sense that it does help, also makes sense that removing it makes no terrible difference. I do know of several motors where very noticeable power was gained by manufacturers using long runners cast into the manifold (pretty sure it is more than 10 HP), I am not so confident of success with a manifold being able to deliver both using a diverter plate. I think the idea is long runners for lower rpm and then switch to short length runners for high rpm. I guess most of us dont use high rpm very much and perhaps the high rpm success is only so manufacturers can label, and sell the vehicle as having higher output (max power is always measured at max revs). I also wonder if the groove likes short runs so that the vacuum gets to the cylinder faster??
In any case if you dont mind the baffle being removed then its a win and less stuff to mess up the groove. I have a manifold the same as mine that I have not opened up yet. Maybe I will take a peak and follow your lead. Think Im doing EFIE first tho...
Kind regards, Neil