feul consumption should go down because its letting it breathe better

well...not go down, but it will increce feul efficiency

 

yeah, it messes up that pesky power deficit. the real difference in sound is from the higher quality and different designs of the sound suppression features of each respective system. like the Greddy Evo can is pretty large, and has a nice free-flowing design, but it also has a good resonator. and that, along with a great fiberglass resonance baffling system in the muffler itself, they can tune it to sound how they want. thats why those cheapey mufflers you get sound so loud. they are smaller than Evo in most cases, and are made more cheaply.

 

plus don't the cat backs tend to try to make there exhaust pipes straighter with less bends so it flows better that is why they usually tend to be closer to the ground. or some are even angled like eclipses and such

 

they try and make it straighter. but usually only the race only cat backs are going to go under the axle and angle out the back.

 

I think angled mufflers on a street car is rice...or it could be the way they're installed on cars 'round here...