I had replaced my resonator when it developed a crack at the weld.
I replaced it with a x pipe sine I had factory duals past the single resonator.
I did notice a tad bit more buzzzing or humming from the exhaust since the resonator was right under the front seats.
(but only for a couple of days)
so I thing you will be fine!
Cant say wether the x pipe helped my mpg because I did this pre-ecomodder.
BUT, It didnt hurt my mpg because I was always paying attention to it.
But if I had a resonator now, and it had cracked, I'd still do the x pipe.