Can't Imagine why Kreg ,did you read something otherwize?   Tom

Kreg check this article out,might be helpfull T
http://www.jetboattech.com/pages/header_tech.html

I wish could remember where I read it. It made no sense to me either? Maybe they were talking about reversion inside the intake manifold (air/fuel) I don't know.  Oh well nevermind.

SLCKREG,

  Yea, I think thay are talking about reversion in the intake.  It seems like the t ram would less prone to problems from reversion due to its longer equal length runners.  The vic jr has shorter runners for the middle cylinders so reversion would have more of a chance of disrupting air/fuel flow in the plenum.
 This is just my thoughts, and is not based on any real knowledge of anything   .

 btw, how is the Daytona coming ?  we like pics ( hint hint   ). heres a link to your boats project thread, in case you cant find it any more   .http://www.socaljetboats.com/index.php?topic=1874.0

You get reversion in both the intake and exhaust. How much is dictated by the cam overlap.
 
In the exhaust, it is only an issue if you start sucking in water from the lake. It also helps create the sound of the engine, and earlier opening of the exhaust valve causes some of the combustion at low rpm to happen in the exhaust pipe - this is where the lopey sound comes from.

In the intake, it dilutes the fresh intake charge, and causes the mixture to be off at lower RPM's. You compensate by running the mixture richer at idle, giving the stink smell and blowing unburnt hydrocarbons out. This is why big overlap cams are not used with anything that requires a smog check. As the mixture is mostly diluted by its own runner, really a TR / single / dual  doesn't have that great of an impact on it.

Greg send me the pics I'll post them up this afternoon Tom