I rode about 90+ miles yesterday without any air filter. I noticed the "chirping" as certain low-load, low rpm situations. For all the harping of earlier posts, I didn't find it that annoying.
This morning I received this reply from Bob Carpenter regarding my lack of air filters:
"We don't run air filters. We have the proper velocity stacks on the throttle bodies. In our 40+ years of building high performance street bikes, we have yet to see any faults without air filters. The engine will eat bugs and dust without a problem. Try not to follow gravel trucks. There are K&N filters available that have an open filtered top along with the perimeter, that don't show very much power loss. However, you'll have no bear claw and they might get in the way of your left knee. We strongly recommend you leave as is. Hope all is well."
I assume he may be referring to the K&N's that HansO runs. As for me, I will be getting something -RamAir or perhaps the NLR's. Maybe I'll just tie a shop rag over the stacks!
As for following gravel trucks -not something I do while riding or driving.