What does that do for you?

It gives you a 5% chance to be able to do it again without waiting 3:20

It will say something along the lines of 'You feel a rush of adrenaline! You need to do that again!'

and you can just do it again instead of waiting for the cooldown time.

Hope this helps.

http://mafiareturns.com/credits/spend.php

scroll a bit down and you can read about all perks

aah it does help! thank you very much

no problem. Also you can go to Manage->Spend and you can buy the upgrade.

Petty Proficiency Perk 1.00 Credit

• Execute the perfect crime. Gives you a 5% chance to not have your timer used when you do a petty crime. You are instantly able to do another.