2006 Sport 1000 has an O2 sensor. On the stock exhaust, it's tucked back in the crossover pipe, just before they come under the swingarm.
Yes, you still get the "lurch" if you try to hold it at 4000 rpm. With the stock ECU, keeping your chain tension within specs helps this immensely. As does taking your bike to ducvet. He's, well, magic.
If you go the Zard route, you'll still have to do something about the O2 sensor. Just letting it dangle makes it run even hotter.
I would go the Termi rout. I dont think it looks as good as the Zard, but it sounds better (IMO) and is almost 1/2 price.