The user control factor comes in because drivers can tune the engine by plugging in a laptop. As Future Power says, you can "drive to the track day economically and up the juice for faster lap times." Future Power has not designed the system for standard treehugging low-emissions vehicles, although it could easily be adapted, couldn't it?
The LPG conversion system will be exhibited in the UK in a variety of "high performance machinery" (including a 300 bhp Subaru WRX) next weekend (Sept. 22nd) in Wiltshire.
[Source: Future Power]