Yeh buddy, I'm running the 06 cylinders in my 05 900 "budget build" (thread in my sig with nitrous)
I have the upper injectors blocked, plugs made by Indy Dan...but did require some thinking and modding to the rear of cyl where the injector protrusions out...to make room for the steering post...I think there's pics in the build thread, if not I have them on my laptop..
Anyways...the 05 porting work that SLP does for $500..is basically what the 06 900 cylinders come from the factory..so it was easier and cheaper for me to go this route...
BUT...I was told by a few people, that porting of 05 cyls (or using 06 cyl) would require using the SLP performance pkg ecu flash or a fuel controller otherwise you could change running lean and burning down...I happen to score a used flashed 05 SLP perf flash ecu..
And you cannot just get the flash from SLP...it's on lock down unless they do your porting, but you can try...otherwise you need afr gauges and fuel controller..
Does that all make sense? I may be confused now, LOL.