Gas prices are low but not for long

Hi, did anyone here experiment with HHO cell or MAP, IAT and O2 sensor modifications and notice significant results in MPG? I made one HHO cell but it probably did not produce much gas so I did not notice any gains. Also tried MAP sensor modification: installed inline resistor in the signal wire so that at idle instead of 1.4-1.5 v my PCM was reading 1V, and engine ran perfectly fine. Also made a swithc for ECT sensor for faster closed loop time with additional resistor which when switched pcm reads signal of that second resistor and thinks the engine is hot. I used this in the morning startups mostly. I would start the engine with regular ECT resistance and then would imediately swithc to second resistor (did not have any problems) after 20 min swith back to normal ect resistance to avoid overheating since the other resistance was fixed at optimum engine temp. Can not believe wtih all this I did not save any gas. :crying: anyone has any othe ideas that work.