According to TURBO-RICK the K & N produces less horsepower than the BMC!
also,
K & N refuses to re-dyno my bike with the new filter...
my busa was used for the Akrapovic mapping by dyno-jet, Las Vegas, Mike Belcher
it had a stock air filter ...
K & N gave me a prototype filter, wanted data regards to performance, etc, which I geve them, but when the new filter finally made it into production K & N management refused the re-dyno to verify performance.
Looks like BMC is a better filter, at least, "privateers" have verified BMC hp over stock filter!