How do I stop the 80 thousand cops responding to backup, callouts and pursuits? 

I'd say you are exaggerating :p

 

But you can edit the INI file. Read the manual to find out what to edit. 

But it's fun! :D

EVERYONE ATTACK!

One thing is don't spam backup or NOOSE keys. When I was playing 0.95, I had to spam keys because backup wasn't so reliable; in 1.0, spamming keys will result in spamming backup units. Each backup call equals one unit dispatched.

Also, in 1.0, patrolling units respond to situations much more effectively than in 0.95, so that may contribute as well - it could be that the cops driving by intervene. If that's the cause, it's pretty much by design - police in real life tend to stop and help if they see another cop who wants help.

You can install a less cops mod, which reduces the amount of cop cars on patrol in Liberty City.  http://gtaforums.com/topic/403696-relivless-cops-around-liberty-city/