You think the specials don't make much of an impact? Well thanks to this mod, most of the spawns during assaults are shields, medics, bulldozers, tasers, and cloakers. Do note this will make the game easier or harder depending how you deal with specials. I made it where mostly shields spawn. If I made every special spawn, then the game would be over in about 12 seconds.

Notes:

Bulldozers spawn on Hard and Normal.
All bulldozer variants spawn on Very Hard and above.
Marshals spawn much more earlier.
Mod works if you're the host.

Known issues:
Polica Federal not included because normal units spawn.
Normal units spawn on the Murkywater faction. Albeit, rarely.
Marshals do nothing

Credits

IareAwesome17's Mixed Spawns as a base.
Jarey's PDTH: Bulldozers for the image I made.

Cool enemy redesigns you can try