Most 'ram air' intakes are just cold air feeds, I believe the Yamaha thundercat was one of the first bikes to run a true ram air setup. And that is far more than just sealed air feeds to the airbox. It has various air chambers under the fairings, and even uses the air to pressurise the float bowls on the carbs to increase fueling to match. And with all that, it's claimed to only add 3hp at over 100mph, and that's on a near 100bhp engine.

Unless your trying to chase every last 0.5hp, I think your best off with a air box, especially on the street.

"I do believe that air box volume in the still air portion is important to lessen engine acceleration issues from inadequate immediate airflow across the filter. Books written on the subject indicate suggested air box volumes needed.
Resonant tuning a two stroke, and even the four strokes brings the discussion of fuel stand off in the carb air inlet bell and extending even some short distance up the air boot. Fuel stand off is a function of resonance. The engine pulses generate a reverse wave through the carb and since not all fuel is consumed on each intake function, the resonant wave tends to carry atomized fuel back to the waves break point. The break point is a function of throttle opening, engine intake timing, and the mass of the air being moved.

On a steady throttle operation, such as the examples posted earlier, a known setup can be made and tested to optimize resonance and fuel stand off. At low throttle settings, and changing throttle settings, resonance seems less important.

I do consider the rubber air boot between the carb inlet airbell and the air box important. Not in a sense to gain a resonance performance gain, but rather to minimize premix spray into the still air box."

Airbox is good on MX to avoid getting dirt/grit into/near the filter.

For a road going daily it makes sense to avoid the filter getting wet on your daily commute.

But it terms of real world performance? I doubt it's much if any. In fact, probably better gains to be had binning the airbox in favour for a pod filter just in terms of weight savings alone

I have no facts to base this on. For me it just comes down to if I really wanted more power. go bigger on displacement.

For me it's just a convenience factor. It's easier to service and rejet on a pod filter when compared to an airbox. It also allows easier access to the important things when it comes to servicing too.

The portgual lot aren't bothered with airboxes and their bikes are far faster than ours.

My guess is that due to their better climate, they don't have to put up with the crappy weather we get here.

BARacing

And does this make the air more denser or not then? Or is air just plain ole air???

I found this really interesting thread for more info;

https://www.125ccsportsbikes.com/forums/index.php?showtopic=104889

Velocity and Density.
Your air box is more then a reservoir, if you want an example of that then look at what the YIES does.
Imagine your air box not as an active space doing stuff but a channel between the areas that make a difference to the stuff that’s happening.

I feel like I can kinda get where your friend is coming from on the idea that you need to have a consistent air flow or a “settled air” but the principles with air and engines seem pretty universal regardless of what it is

So disregard the fact it was a learner legal 125, these things were well spec'd.

Aprilia aren't thick, they know what they're doing.