A little local business here in Devon makes a higher spec device that bubbles away producing hydrogen and oxygen, and then feeding it through the air in take. I had this fitted, and so far so good. No dramatic difference, but emissions are improved by more complete combustion. I am measuring fuel economy - hoping for 15-20% improvement, which may get me to 28MPG from 24 - whoohoo! The device draws about 3 amps, so no issue for the battery. I will keep you posted once I have measured any improvements.
