How much flow you need is based on two things:
1.) Power developed.
2.) How often cleaning will be required.
Until you have an aftermarket full exhaust system (including a well designed header), you simply do not need a lot of intake filter area. K&N RU-2780 filters (three) are not particularly high flowing, and the intake length is shorter than the stock plenum runners. This means that the stock plenum tends to make better torque at low rpm (under 4000 rpm).
Once you eliminate the exhaust header as the restriction, then you need a good bit more intake flow (and length

).
With the R3 engine specs, the top of the stock rubber velocity stacks in the stock plenum give an intake length (not including intake port) of 6.5 inches. Revving to 6000-6500 rpm, the engine really wants an intake length that is a good bit longer. Anything less will reduce torque output under peak torque rpm.
When combined with a well designed exhaust system, a well-matched intake system can deliver output (HP and TQ) gains that are truly impressive compared to stock.
Below are a couple of photos from some early development. The first uses the stock velocity stacks and a large filter. The second is for the same filter, but better shaped and longer velocity stacks. The latest generation is even more impressive, but requires a custom replacement for the Bearclaw that includes a scoop.