This is a very difficult question to answer. Altering the airflow path before the airflow sensor can lean out an engine, which might improve performance, but cause unnecessary heat and stress. Without dynamometer testing with careful monitoring of Air/Fuel ratios, any changes are speculation.
Your current installation is probably particularly sensitive, since the filter shape has changed, and the distance to the airflow sensor is very short. Vortexes and boundary flows will not have much time to settle out, and may not be laminar flow across the actual sensor wire or film - which may cause significant discrepancy between measured and actual airflow.
Obviously you want the largest and coolest amount of air you can get, but figuring out this configuration will be difficult without a lot of repeated trial and measurement. "Bigger" is not always better.
The only other possibility is to closely copy a proven "aftermarket" system, but even this strategy has risks, as not every single aftermarket vendor is perfectly honest. [cough] Some of the performance gains printed on the box are at the cost of tricking the airflow sensor into running lean.
The truth is that the OEM airbox is typically of excellent design, and the Mass Air Flow sensor scaled to the particular characteristics of that design. Changing a filter element in the stock airbox to a different brand or style (e.g. K&N) will not likely be a problem if properly maintained.
However, redesigning a complete Cold AIr Intake system, without years of engineering experience, access to a dyno and other measuring/logging equipment, and a lot more time and money than the result would be worth, is simply not a good idea in my opinion. Also remember that you are ultimately limited by Engine Control Module programming and fuel trims, and you are "using up" the ability of the ECM to compensate for other variables. To truly take advantage of a modification that affects (and improves) Volumetric Efficiency, the ECM must be made aware of the modification and reprogrammed to reflect the changes in its air/fuel ratio and timing tables.
So... in order to make certain this really IS an answer, I would remove the conical filter, restore the stock airbox configuration, and purchase a bespoke K&N type oiled gauze filter to replace the stock pleated paper type. I honestly don't think that cone filter arrangement is going to help you. I do like the way it looks, but ultimately I doubt it will help, or perhaps even harm your overall performance.
