First: To get a better sound of pops and bangs (crackles) you need to remove catalytic converter and install mufflers.
Second: In 3ur-fe engine don't expect the pops and bangs to be loud like other cars, For example its won't gives you the crackle sound by downshifting like other cars, its will give the crackle sound only in a high rpm (between 3,000 and 5,000 rpm) and you must press the throttle a little bit or no crackle sound .
(Notice: High RPM + Pressing Throttle Little Bit = Crackles !)