I'd put a cat on. It's a federal law that says it has to be there, doesn't matter if your locality tests emissions or not. I picked up the Tracker's high flow cat for $85 delivered off of eBay.
My second Tracker had a cat and no muffler. Sounded decent. Like this one better with a Magnaflow high flow cat and a Cherry Bomb.
Thought for the day:
Go find a parts place that has pre-bent pipe, shoot the breeze with them, tell them what you need, and start playing "does it fit" with 2.5" bent pieces.