Ok this is from someone who does not know much about engines but just wants a faster car so forgive me if I ask stupid questions. first whats the difference between the Jim Wolf Pop Charger and the Injen Cold Air Intake and second which is the better of the two options. Anyone replace their muffler that hangs down way to low on the murano. If so what did you use and did it improve performance at all. I want I a nice powerful muscle sound.