I did buy a Bos Titanium exhaust for my Zx6R 3½ years ago... Smashed the bike up properly on the day I received the exhaust so never got to fit it.
Can only say that they are quality!! I love that it had a fitting bracket rather then a strap which makes it look much better.
They guy who I sold it to was well chuffed with it!
I have been in contact with the Bos Technical manager as well. Very helpful and friendly people!!
I can't fault them except that they are a bit pricey - but hé... you gets what you pays for
