I figured it was a long shot. I seen a pair of M4s for sale on eBay going for 280. I might get those even though the carbon looks to be peeling and it doesn't come with the supports.Welcome to the forum. There aren't a lot of new aftermarket exhaust options remaining for the FZ6. This was recently discussed last May. Leo Vince systems are still available, and they are very nice. Here is the thread on the topic:
Do any reputable manufactures still produce exhausts for the FZ6? Having trouble finding an exhaust for my bike. Trying to stay away from the eBay route. Would love a Two Brothers but it seems they are discontinued after talking with them on the phone.. and I’m guessing most other major name...www.600riders.com
You can wait for a used system to come up for sale...but you'd probably move on to another bike before one becomes available. Check the motorcycle salvage companies. An exhaust is a common upgrade, so a lot of bikes being parted out may have the systems you are interested in using.