I just got my Ralliart last week and want to get an exhaust for a deeper sound. If I do this, will it affect my mpg? Will the car rev higher? Does the car's computer need to be reprogrammed? Will a new muffler do it? I know these questions sound funny, but I'm new to all thanks for your patience!

 

It shouldn't have a noticeable difference in gas mileage, the car will not rev higher and no the ECU doesn't NEED to be reprogrammed.

That being said you are much better off getting the ECU reprogrammed (Flashed) to see the better gains from the exhaust system. Assuming you do a full catback. Otherwise it's mostly just noise.

 

if you want noise just get from the catback or axle back exhaust