In SR4, the crash program action was an extended test: Hacking+attack (Firewall+system, 1 combat turn), but this action was changed in SR4A to an opposed test: Hacking+Exploit vs Firewall+System. Nevertheless, there are some rules in Unwired which should be changed because they use the old SR4 extended test:

The crashguard program option raise the threshold of the Crash action by 4. It should be changed into a modifier to the Firewall+System test, I suppose... but the rating should be +4 ?

Now, the Shredder program option must be used on exploit program, not on attack program.

But what about the disarm program? Should the disarm action be changed to an opposed test, too?

Threshold of 1 usually equates to pool modifiers of 3 or 4, on the basis each 3 or 4 dice rolled gives 1 net success.

Yes, but the threshold +4 from crashguard is for an extended test. It can't be translate into a +12 bonus in the SR4A version of the crash program action.

Indeed, I suppose that the new SR4A version of crashguard should be:
"give a +2 modifier to the concerned program in the test Hacking+Exploit vs Firewall+System" OR
"give a +3 modifier to the concerned program in the test Hacking+Exploit vs Firewall+System" OR
"give a +4 modifier to the concerned program in the test Hacking+Exploit vs Firewall+System"

Which rating from +2 to +4 is the best solution, in your opinion?

Do you still use the Disarm program as written in Unwired or changed his Hacking+Disarm (Firewall+System, 1 Initiative Pass) extended test to an Hacking+Disarm vs Firewall+System opposed test (in the same way that the crash program action was changed in SR4A) ?