Who says you are getting downgraded?
perhaps I have been misinformed, but what I have read & been advised about the bolster mechanic is that it will "normalize" (that's probably a better term than downgraded) gear stats across the group so that essentially everyone has a 162ish ilevel. If you are under that ilevel, it moves you up. if you are above it, it moves you down.
Reno, please tell me I have misunderstood or was misinformed.