I considered cafe4racer.eu, but noticed that their website has no specification for the silencers or description of their workings, only a picture. I emailed them to ask. Turns out the silencers are just pipes with no real silencing going on, whereas I'm not looking for a loud bike. Then I looked at Bsk Speedworks and Supertrapp and ended up getting the Supertrapp Aluminum Race Series model 422-25000, which many have used on K project bikes. Just installed it, love the look and the sound.