I need a resonator to quiet down my header . I happen to have a $20 gift certificate for summit racing that will just about cover the cost of me buying a glasspack vs the $70ish it would cost to buy a maganflow resonator. Does anyone have hands on experience using a glass pack on the focus? I guess my main question is longevity. I realise that it will eventually burn out the glass but how long would that take on a focus with a race header? I figure it should last longer than on a V8 like they are kind of intended for simply due to the smaller engine should equal less heat?