Well...it's kind of outdated now for one thing.
Another issue.....there are two air filters feeding into the same piece of common pipework,with the diameter of the MAF being the narrowest point of the system.
The law governing the flow of gas and the onset of turbulent airflow is determined by the following factors:
Length of pipe
Viscosity of gas
Pressure differential across the pipe
And most importantly is inversely proportional to the 4th power of the radius of the pipe.
Now the end point of all the physics is this....it doesn't materially matter if you have one or ten filters feeding into the same piece of pipe if the limiting area is downstream at the MAF.
So...the best current intakes are,in no particular order,Revo,ITG and AMD,all of which have smoothly curved pipework,reducing the onset of turbulent flow(which results in decreased flow for the same pressure differential).
And finally,if you get an increase in flow as a result of fitting two filters feeding into the system,it means that the limiting point was an air filter with an inadequate maximum flow rate.
Please....don't get me wrong on this.....Forge make some excellent products,and deliver excellent service.....I just don't rate this one.