If I take the resonators off when I get flowmasters, will that hurt my gas mileage?

 

Resonator is strictly to control the raspy noise that you hear inside your cabin while driving.

 

No, will not hurt your gas mileage at all. I will make the cabin noise much louder though. You may want to see if you like it with the resonator before removing it. I ended up getting rid of the factory resonator because I wanted more tone, but replaced it with a smaller 14" resonator (stock is 18"). This was perfect for my taste.