Has anybody out there actually tried them?

The only person that I know who is running Decker pipes is Kelsey at RKT Heads. You can get his contact info at RKT (http://www.2strokeheads.com). He will be able to answer any of your questions. He is running them on his Ski- Doo Rotax Series III 734cc Big Bore Kit for the 600Ho and 700.

Pierre

do yourself a favour and buy Crankshop pipes if you are going to spend the money