There are not a lot of filters that are going to fit under the unmolested bearclaw other than the RU-2780 - there are a few, but not many. If you are willing to cut or remove the bearclaw, your choices increase - and you can decrease air temps, while increasing flow and performance even more. Even the RU-2780 produces approximately 3% more output with the bearclaw removed - but you will need to correctly tune for best results. And even more output is possible with higher flowing filters - significantly more.
If you go on the K&N site, you can perform a product search for filters (round, oval, conical, tapered, chrome top, X-treme top, etc.) with specific dimensions.
Search for filters with a flange inside diameter from 62mm-65mm and you will find a host of choices including this one:
Even DNA Filters offer a couple of options that will fit on the throttle body flange.
Part numbers
OV-6500-16 and
OV-6200-7 are just two options from DNA.
Locate a filter that will fit you needs, and with as much flow as possible. Excessive flow will keep the filter from becoming dirty quickly and reduce performance within a short amount of time. You would be amazed how quickly the RU-2780 performance can be reduced with even a small amount of filter clogging - and it is hindered by flow restriction to start.
Also, realize that locating the air temp sensor so that it picks up air at the same temp as is entering the engine is important. The sensor data is only updated every 7-10 seconds, so keeping the temp correct, and not excessively heated from the engine, radiatior, etc. is important for corrections to air temp in the ECU and best/smoothest output.
Over the past several years, I have tested a great many filters, air/heat dams, velocity stacks, and much more. There are substantial gains to be had when improving the intake system. I have tested flow on a bench through the complete intake and head, temps with K-type thermocouples, velocity with pitot probes, and restriction with a magnehelic gauge. You will be amazed just how restrictive some of these common filters are, and how quickly they become even more so with a small amount of dust/debris.
The 2.3L engine needs a given amount of air to become efficient. As you improve the exhaust system the intake demands increase substantially - even more so with compression, head flow, and camshaft improvements.
Simply decreasing intake air temps 7.4º F will increase output 1% and improve response - even at very low engine speeds. You might be impressed how much it is possible to decrease heated intake air from the engine and radiator. Who wouldn't want their bike to have the crisp response of a cool evening evening on a hot Summer day... and the evening air becomes even better.
I hope this helps.
