Why Muffler increases gas consumption

do you need a muffler,exhaust system,exhaust system explained,here's why you don't need a muffler,muffler explained,stock muffler vs aftermarket,what happens if you remove the muffler,why not to change your car's muffler,why not to have a muffler in your car,Muffler increases gas consumption,Change muffler good or bad,Hks muffer,Bad impact of muffler,Muffler affects engine,Muffler increase gas consumption,Why muffler is bad for engine,Why not to install muffler