Any non aromatizing steroid is gonna make you look harder and more vascular if u have low b.f., but it is not going 2 lower the b.f. in and of itself....that is done thru diet and cardio.
I would imagine anyone that lost 8% b.f. off a winny cycle probably had pretty high b.f. to begin with and was either not in the greatest shape or drastically improved/increased their workout routine during the cycle.
No matter what the case, something else was changed or altered (diet/workout) that caused those changes besides just taking some winny