5 mpg per plug?? what the hell are you on? you would only get an increase of 1.5 mpg at the most with a 3.4 Do you even own a car with a Quad cam 3.4? I own a 1990 Grand Prix with a 3.1 Multi-Port, and a Z34 Monte Carlo with the 3.4 Twin Dual cam, and both have those mods. I know what I'm talking about