All the 800 Sportsmans (Sportsmen?) have dual exhaust, I think about all it gets you is 14 extra pounds for the second can.
Polaris slapped the HO moniker on the 800 in '08 to denote a boost in engine performance of about 4 horses. Dyno figures I have seen for the '08 put it at 54.8 HP stock, and the '07 models at 50.7 HP . Really 4 horses isn't bad, I believe they did it by tweaking the fule curve, mine ran pretty rich before I put a K&N filter on it. They K&N leaned it out some, maybe gave it a little more tug off the line and really improved the throttle lag on snap opening.
Q