These product can damage engines. They do not work at all. The EPA knows this and has tested them and found that they are misleading and dishonest, and that they are at best useless. I am a motor engineer with 35 years experience with designing and modifying fuel systems.
I have many motor engineering friends and business associates who are very angry about these lies. I have 2, 500 automotive workshops as customers. Not one of them believes this crap. Problem is, if people do not understand the laws of thermo-dynamics they get sucked in and ripped off. I have all the test equipment to test these devices. Dyno, 5 gas emission analyzers and DEA MEA analyzers with D.link, so I can test all of them. I do not bother any more as I know the outcome. Please stop dealing with these fraudsters.