I want to say that I beleive the Jenks product is a fine product and a great alternative for those wanting to keep their airboxes "stock", but improve the power potential of their machines.
However, I believe there is some confusion about what a velocity stack is and does.
This thread is probably in the wrong place, too.
That said;
Quote:
Not necessarily true. The idea is to speed-up the airflow as it makes it's way through the intake track. That's why you see such devices on automobile mass air sensors, way up-stream of the throttle body. The velocity stack compresses the air charge, both speeding it up and cooling air temp. Merely pulling-off the snorkel is not going to give you equivilent performance as the velo stack. That's been well proven over at the 360° camp.
/Mike
I respectfully disagree. 
There are velocity stacks at MAS' on cars because a velocity stack is an efficient design.
Velocity stacks do not "compress" air. Compressing air would actually heat it up, and thats not desirable. What they do is increase air velocity and smooth air flow by improving on an inferior design. It is possible to tune for power in a specific range of the power band (i.e. midrange, top end) by adjusting the length of the tube, but the tuning would only effective on a very finely tuned and high performance machine. Our vacuum slide carbies would likely not react to such incremental tunings anyway- way to imprecise. But other than that, a velocity stack does not actually make power.
I guess the point I'm trying to get to that a velocity stack is nothing more than a very efficient intake design.
Adding a velocity stack vs. pulling the snorkel only improves on an inferior and restrictive intake design. Just as pulling the snorkel increases performance over stock, opening the the intake port and shaping it to be conducive to air flow (drag coefficient of 1 (a VS) vs .9 (a blunt tube)) will increase performance.
This can also be achieved with inverted velocity stacks within a high flow filter.
Hope this helps 
