It IS possible for a bulb to start the arc, and yet not produce optimal lighting. However, this occurs very infrequently, and is therefore unlikely.
The most likely cause of poor light output (especially if there is no colour shift (bulbs are the same colour)) is that the focal point of the bulb is not aligned correctly with the headlight housing. First thing i'd do is check that the bulb is sitting flush with the mounting surface in the headlight.
I run a canadian led kit & hid kit company, if you have any questions about led headlights or hid kits in canada or would like to check out our products please contact me here: http://absolutehid.ca
2002 TiAg M3 6mt
deoranged, dechromed, led tails, ZHP knob, UUC SS v3, GROM, OEM 220M 19's, Michelin Supersports
2006 YZF-R6, black, ohlins, pazzo, BMC, cat delete, vance hines csone, YEC racing tune,-1 +2