tuck2, you seem to be up on ProCold nuts... kinda wierd...

 

well it's obvious he's with procold

 

Here's my data on intakes: (numbers from EFILive used for comparing mods, not dyno numbers)

1) Stock air box, stock tube ~380-390ftlbs torque.
2) stock air box, stock tube, ram-air mod bottom of air box ~390-400 trq (cylair ~ 0.79-0.81g/cyl)
3) stock box, K&N tube, ramair ~375-390 (cylair ~ 0.76-0.77g/cyl)
4) K&N heat shield + cone filter, K&N tube, ramair ~375-390

I think the comments about the resonator chamber in the stock air tube are correct. The chamber is a Helmholtz resonator that reduces intake noise. It also has the benefit of providing a little extra air volume during the transition from part throttle to WOT.
Look at it like this... at part throttle the TB blade is the restriction in airflow, but at WOT, the air filter becomes the restriction. The chamber on the intake tube has extra air in it to feed the engine when that first big suck happens at tip-in.