I can sort of understand why Hilltop threads become so adversarial – because people have spent significant dosh there. Ironically, those of us questioning what Hilltop does to your bike are trying to do so for others' benefit, i.e. not wanting fellow bikers to be paying for something they're not really getting. However, I now understand that if I write the truth about Hilltop then my posts or indeed the whole thread will be deleted by the moderators, as has happened recently.
Therefore I'll join the herd and say that Hilltop is the best £350 you'll ever spend on your bike. It's better than a PCV because a Hilltop remap self-learns and adapts to any exhaust and air filter changes you may make in future. It is completely undetectable by anyone in the world and especially not BMW dealers or insurance investigators. There's a great chip shop around the corner and Geoff's a great bloke who tells side splitting anecdotes, so it's worth travelling from far and wide to Earl Shilton. He has remapped numerous BSB bikes and even gets pre-launch road test bikes to remap before the motorcycle journalists get their hands on them.
If you want to understand exactly what Geoff does to your bike give him a call on 01455 848522. Here's a link to his website
http://hilltopmotorcycles.co.uk/