If you choose to not use the manufacturer recommended oil filter, than how do you answer these questions regarding the oil filter your using?
1) How do you know the paper filter element flow restriction doesn't cause a back pressure to develop and trip the bypass valve during normal engine operation and within the oil filter service life? How would you ever know this is happening?
2) How do you know the bypass valve is rated correctly for your vehicle?
Ok, I'll bite as this may be helpful for all.
Remember, pumps, any pump, like an oil pump, does not create pressure, it only creates flow. Pressure is created as the result of the most restrictive orifice to the flow the pump produces. Maximum pressure head is expressed as an "x" tall column of water for a pump and this "pressure head" is the maximum amount of back pressure a pump will stand before the fluid goes back through the rotors, vanes, or blades. It is at this stall point that things start to leak or explode in really bad examples.
In response to your question #1, regarding the permeability or lack thereof of the filtering media of a Kawasaki OEM Filter, A Fram Filter, or a Purolater filter, you will not ever know when the bypass valve opens or reseals. In fact, this happens now, on your bike and mine, more often than you would think. The BYPASS valve is just that. It Bypasses oil around the filtering media when pressure on one side of the filter media is greater than or equal to the bypass valve setting pressure on the other side of the filter media. The most often times this happens would be after a cold start and the oil has not warmed up and you decide to go full wheelie mode hitting redline through all the gears. Maybe you have decided to run 90wt oil in your engine... much bypass valve action will be happening.
The second unstated underlying part of your question #1 concerns the filter media performance as to how it relates to the bypass valve. For instance, if you never change your filter at all, I can guarantee that it is full of sludge and the bypass valve will be in operation to try and save your engine. Unfiltered oil is better than no oil at all. Past that scenario, comes the question of filter media performance. A larger filter with more sq in of filtering media will flow oil better than a smaller filter with less filtering media due to the increased surface area of the larger filter requiring less psi to push any given volume of oil through the media. Given that the filter media is of the same type in each filter, the larger filter will have less bypass valve action and flow more oil with less pumping losses versus the smaller filter.
Question #2 is a little scurvy one as Kawasaki does not publish oil data in their manuals. Kawasaki says Oil pressure should be 42 - 56 psi @ 4000 rpm but does not list an oil filter bypass pressure setting or relief valve setting pressure. However, Yamaha does. Most Yamaha's spec a 5GH-13440-50 filter. Most Kawasaki's spec a 16097-0008 filter. Honda's spec a 15410-MFJ-D01. All these filters spec back to the beloved Fram PH6017A filter, so says Fram. So, a lot of filters, by exact spec, from a lot of manufacturers, can replace the KAW OEM filter, by published spec... Did I mention "by spec"? By looking at the Honda & Yamaha specs, I can really go out and get whatever filter I want. If those filters spec back to the Kawasaki, then that is really good.
I wish I could put pictures in the text here as I want but I think they are shown below for all the data that you want to see.