As the others have suggested, noise is really going to depend on the pad compound. I've been running the Z-rated street pads with no problem. If you're running a more track oriented compound, then some noise is to be expected. It's also possible you have a piece of gravel stuck somewhere (often trapped by the dust shield) but this seems less likely if it started immediately after the pad change. Was any anti squeal compound used on the backs of the pads during the install?
04 IR 330i ZHP | ESS TS2+ SC | MagnaFlow "headers" | KMS 3.64 LSD | AST 4100 550/650| APEX ARC-8 18x9 | H&R front sway bar | Vorshlag camber plates, RTAB limiters | TMS subframe & swaybar reinforcements | UUC SSK & DSSR | UUC TM & TME | BW motor mounts | Dinan strut & shock tower bars | vaio 4-bolt oil pump