You can always go with a Kakimoto or similar 70mm (~2.75") exhaust. You need to make sure whatever exhaust you go with has no bottlenecks...if the piping is 3" but tapers to 2" at the muffler, its pointless. And a 3" exhaust is not needed to make the most power....depending on your setup, 2.35- 2.75" piping may be optimal.

And any 3" exhaust, turbo or not, although not would be ridiculously obnoxious, is going to be damn loud. Serious highway dronage. Especially with a straight through muffler.