Hi MuuuMuu.. I believe that a new car, designed to work with NG would have the same performance as a gas car. The problem is that our dodges were desiged to work with gas. Moreover, nowadays we have electronic fuel injection system. This makes a huge difference.
The muffler sounds (like fart) occurs due the NG kit. The NG kit pulses the gas trough the engine.. we rear a muffler sound like a toc toc toc toc (farting).
A friend has a modern car with NG and he said the he does not feel any loss on horse power. His car is a GM 2.0 Vectra
