I also took my IS250 there after you mentioned them. Cost was £340+VAT (£408) for the rear section including both rear boxes and new tips. They did need it for the whole day, and there was a 10 day waiting list as it were. They are now called Cybox if you want to look them up. It is a little louder now, although I did specify the quiet option. Cant really complain and I would recommend them. As mentioned above a lifetime guarantee is standard.