Can I replace my exhaust system (cat back)with a larger diameter exhaust system?

What is your question?

I have a 2004 Saturn Ion2, OEM exhaust system has a diameter of 1.75", I want to replace it with an all stainless steel aftermarket cat back exhaust, but the only thing available is a 2.5" diameter exhaust. I already know that a minor modification has to be done to make it fit, other than that, are there any drawbacks besides the modification that has to be done when going from 1.75" to 2.5" exhaust?