I've just fitted an Arrow to my cbf1000fa. I have to say, I don't know whether to be happy or disappointed. Yes it's given it more character (noise), and it seems to have more bottom end grunt but it's lost that silky smoothness at about 2500-3500rpm that I loved so much about the bike. Now it rides just like any other inline four. It used to glide nicely at low revs. I don't know how to feel about it to be honest.