The single piped ported 800 I ride with is hands down better running than my piped PCV. When my warranty is up, I will be sending it to Carls. On climbs, there's about a 3-4 sled advantage and a much more crisp throttle repsonse. 155's with the stock tracks with the same helix and gearing.
Rumor is the Carls twin piped ported 800 will run with the single piped 860. But I haven't ridden the twin piped ported sled so I couldn't comment. The 860 runs pretty good so the twins must make a big difference