2013 rear end\tire combination overall ratios

I'm thinking of ordering a 2013 V6 manual transmission mustang. I would like have a sportier suspension system but want to keep the highest mileage. The suspension "performance package" adds 19" wheels instead of 17" wheels and also a rear end ratio change from 2.73 to 3.31. I like the 19" wheels but don't want a setup gets less gas mileage. Does anyone know the difference in overall drive ratios with the two rear end/tire combinations?

Thanks,