they say that because if your fuel solenoid goes bad you spraying straight n2o into your engine with no fuel to compensate, n2o solenoids have 1000psi behind them, fuel has 42psi... how often do you think the fuel noids go bad? Nitrous isnt really something you want to be a first time installer of unless your willing to fix a blown engine. i would have a professional install the first one then learn more about how it works and so on then maybe install i larger kit yourself later. btw the guy that told me about the pressure behind the noids and why the fuel one never really goes bad is really smart
