The Combine Voices Mega Sounds Pack
Containing voices from PAYDAY law enforcers and (in the alternate version,) Black Mesa grunts. Contains over 1000 different sound files. I admit, however, metro police have much more variation in sounds than combine soldiers.
Not only does this heavily modify the sentences.txt it also replaces most scripted map lines, some with specific lines you won't hear anywhere else. For example, the cops knocking on Barney's door in d1_trainstation_01 and the two cop's conversation in d1_canals_01a. Does not replace the "pop can" cop's lines.
Installation instructions and credits included in readme.txt
Preview for alternate: