For a K11 you would get a streetblaster 100i kit, which would be a 25bhp increase (believe me this is alot, ask anyone who has been in the ST) you can increase this later, if you have not killed the clutch already... This is £489, for the 5lb bottle or + £48 for the 11lb bottle (the one I have). Fitting is surprisingly simple, although I would need to check a few things before being able to give advice. If you added this to a K11 which already had the usual exhaust and intake mods it would be RAPID to say the least!! 100+bhp@wheels haha.