I understand the concepts. On a stock motor with a KN replacement filter in place of the the stock one I doubt you will make any horsepower gains. Pretty much the same with their "cold air" intake. The air restrictions on a stock GenI motor are not the airbox.It's all relative.
On a stock motor yes, maybe.
The bigger the need for air, the bigger the HP gain.
If your motor needs 1500 -2000 CFM the gains will be bigger with a K&N
On a Honda, not so much.
The higher the perormance, the less restriction benefit is realized with K&N.
Top Fuel and the like don't even use air filters. The engine would just suck it in!
But they rebuild it every run anyway.
Back in the day, withbig V8 Carb motors we would remove the air filter on Street racing.
We also used 104 octane thinking that would help, but what did we know as kids?