So, what do mufflers do besides making noise and look cool?
Do they actually get performance gains or what?

 

not on a civic unless it has a potato clogged in it. they're mainly for sound. if you want a little bit of performance, then get a catback system.

 

Mufflers actually muffle the sound of the exhaust. The stock muffler is restrictive so opening up airflow passage is good. Unfortunatly unless your civic is turbocharged, supercharged, or running some kinda crazy compression you wont see any performance gains. If you want to bypass the whole system itself, you can get an exhaust cutout, its loud as hell but i think it shows the most hp gains but you would have to delete your rear o2.

 

that's pretty funny because the majority of civics I see driving around where I live have "mufflers" that don't muffle anything at all. ricers

 

If your talking about stock mufflers, they are there to muffle the sound the engine makes, broken or open mufflers (aftermarket) let the sound come out a lot more because they arent restricted and will give a little better performance (dont expect to be killing mustangs)

 

I currently have stock exhaust... the really basic one. If i get a new exhaust that lets more exhaust out, would that be good for engine and stuff?
BTW, if i usually drive at 50 to 60 MPG, how would leaving the moon roof open do to the gas millage?? gas is super expensive now

 

50-60 MPG? or MPH

 

^^ lol, stupid typo by me...
I drive at 50-60 MPH.....
how would leaving the moon roof open do to the gas millage?? gas is super expensive now

 

if you're that desperate to save money, i suggest just cutting back on driving in general, or cutting back on the cheeseburgers. an open moonroof won't affect gas mileage that much at normal road speeds.

 

at 50 - 60 there will be a lot of wind slowing you down, maybe if you use the tilt feature instead of fully opening it.