There are 6 things you need to do to get this
1. Blow up 25 gang controlled vehicles in 60 seconds
easiest way to do this is by getting a hit squad to go after you and using rockets and grenades.
2. Kill 15 gang members with your bare hands or thrwon objects in 60 seconds.
easiast way is when you have maxed out strength go do a time trial of any of the Los Muertos boss's.
3. Kill 15 gang members with your gun in 60 seconds
You can do this in any boss location
4. Kill 25 gang members with explosives in 60 seconds
For this one just go to any boss loction and use only your rocket luancher and grenades and you'll get it
5. Use vehicle to run over 10 gang members in 60 seconds
The best way to do this is by holdng reverse and left or right. Do this ina big group of people. The best place for this is the area around Violetta Sanchez, Los Muertos Boss
6. Pop 20 tires on gang controlled vehicles in 60 seconds
What you do is get 5 gang vehicles there doesnt have to be any one in them and line them up and aim at their tires and pop them. I got this one by lining 5 Los Muertos cars in the Sports Complex.