Oh dude for crying out loud. Some reading before posting helps!
Every setup is different
Every dyno is different
Every tune is different
Every persons location is different (and this climate can be a factor in tunes)
You want any more possibilities?
Dyno results are a good guide, but to split hairs over 8rwkw is pointless.
If the dyno he is on, reads 10rwkw low, and yours reads 10rwkw high, then all of a sudden its 28rwkw.
You'll NEVER KNOW.