Originally posted by DemonSVT:
Rara-
So you don't think something like a custom advance curve and A/F tuning on a modded car will alter the optimum IMRC opening point then?
Neither will significantly alter the flow volume and flow characteristics, so no, I don't think either will make changing the IMRC opening a worthwile mod.
What about the many different lower intake diameters used? Still no change?
What many different intake diameters? A change large enough to do more than slightly change the intake flow characteristics might make it worth while, but a change like that would likely only be made w/ other significant changes that warrant the larger runners (ie larger valves, ports, etc.) and hence the need to revisit the IMRC controls.
Fair enough... (still going to test it of course 
) Ok. I'm all for additional testing. Just make sure your tests are not compromised by uncomparable methods etc. as so many of the "rags" tend to do on their comparison tests.
What are your thoughts on total removal of the secondaries then? Only 3L or Forced Induction or not at all?
On a street driven car, I would say do not remove them (with a few exceptions) A street 2.5L SVT w/ heavy breathing mods (full, well designed exhaust, oversized TB, intake tract, etc.) can get away w/ it, though the results will be less than optimal (gr8ride's car is a great example of this, his car has some top end gains associated w/ these mods, though I really think he has lost some of his tq in the low and mid ranges. I will admit though,, his car w/ removed secondaries runs better than I expected.)
Similar thoughts apply to a 3L setup, unless it is heavily modified, and maximum peak hp is desired, rather than maximum area under the curve.
Forced induction, I think (though I have not tested this) could benefit from removed secondaries, (turbocharged engines prolly more so than S/C) more than other applications.
