Yeah, I probably should have specified that I was actually referring to the exhaust side of things.
Speaking of the intake side, fuel injectors are usually pretty close to the intake valve openings, so I can't imagine that turbulence is helping much with breaking up the liquid molecules at that point. Doubly so for a direct-injection vehicle. It does seem like it could help matters somewhat in a TBI setup though, since the air/fuel mixture actually travels through the intake in that case (get a "Tornado", LOFL). I bet it may be difficult for the intake manifold to be limiting the overall flow through the entire system BEFORE the exhaust system would, given back pressure at the turbine, mufflers, cats and all that.
If you are trying to eek every last horse out of a specialized setup, at some point would it be safe to say that characteristics that are conducive to velocity and smooth, laminar flow will outweigh any benefits that a rough wall may give to the a/f mixture? I mean, at it's lowest common denominator, the power an IC engine can produce is based on how much air it can pump through it. Meh, maybe I just answered my own question.
"We exist to do great things." -CT Kassem
. '96 Jeep Cherokee XJ "R2" .
. Bring on the apocalypse .