The bike with the O2 sensor bungs belonged to the dealer. It was supposed to be for the dealer employees to ride when leading the demos, but after proving myself on the stock bikes for a few runs I talked an employee into letting me take it for a spin. That thing was a beast to put it mildly. Still had the stock exhaust too (I'm assuming a dealer isn't allowed to sell bikes that don't abide by noise regs?) so with an aftermarket exhaust it had a lot more potential.
The only information I could get was that it had an 88" kit, couldn't get a definite answer on headwork or cams but it felt like the power fell into different areas than the other XB's I've ridden so I assume it at least had a cam upgrade.
By far the most fun bike to demo was the XT. I had no idea that a bike that tall and comfortable could feel so nimble. WHEW! I definitely fell in love. Rode the CR once too which turned out to be absolutely terrifying and I had enough self control to bring it back, park it, and avoid it for the rest of the day.