i've never tried the kanai engine, so i'll just keep it general.
after trying both 086 and 063, I thought the 063 was better, had a much livelier lowend and just hit topend quicker - and it wasn't lacking up there on topend either.
If you have any need/want for a nice kick down in the lowend, try the 063 i'd say.
I've always used RB pipes, so don't know the other side of the argument - but i've been told the Ofna's don't perform quite the same as the RB's, since they are thicker, and the RB's are thinner to help them resonate better or something like that.... (so says rody@RB)
So i'd reccomend the RB (totally based on what i've heard here, I used to think the Ofna/RB's would work exactly the same) but be prepared, since they (RB) get dented up REALLY easily.
Another nice pipe (this one is next on my list) is the OS T-2050. Supposed to make good power all round, kind of comparable to the 086 i've been told, but you can bring in more bottom end with a waller adaptor too.
And it's a lot more durable than the RB's etc, you won't go denting or smashing the stinger in on this one in a hurry.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBPK8&P=7
it also seems to work well over a wide range of engines - RB, JP, Nova, OS, etc, so i'd imagine it'd go well with the sirio too.
-uDi