i have a 2008 charger r/t and the sound just doesnt live up to its name.....my cousin tells me that when you are going slow it has a fuel saver mode, is that true?
and i want to know what the best reasonably priced system or parts i can get to make it alot louder and meaner......any suggestions

The MDS (multiple Displacement System) will shut cylinders down (usually at cruising speed) to save fuel. It is a good system and operates in micro seconds from on to off. My 300C Hemi has it as well.

As for exhaust, I'd look around in the Charger area for suggestions. Most lose the "suitcase" muffler for a pair of free flowing mufflers. That adds some Horsepower back and rumble!!