Exhaust mods for fun?

I told myself years ago, "I can mod this car (2012 v), but I'm not doing anything that noticeably decreases the fuel economy." So no roof racks with massive light bars, as sick as that would be, for example.

I am running out of ideas (no pics yet...work is still in progress...presumed capstone project should be next year).

One thing that did occur to me--has anyone here replaced their exhaust (or part of their exhaust system) for fun?

I'm curious if there's any reasonably-priced component replacement that can be done, specifically to make the engine noise a lower pitch/tone, but not also affect the fuel economy, cause warning lights, and/or be louder than the stock noise.