In the UK the stock 'bazooka' silencer is £500, if you want to buy one new. I'm keeping mine because after 3 years from new, all bikes and cars ( and vans etc) have to have an annual MOT. one of the the things that is checked is the exhaust system - does it have the necessary markings on it, what are the emissions? Is it road legal for the UK? I am not sure that any of the after market silencers for the EFI engines are, because they don't have the CAT converter the original has.