is it normal when I put from park to drive and shift it immediately to reverse it will create a bang sound? No shifting delays and new atf
honda civic 8th gen 2011
While moving or stationary?
Mileage?
89000 milage. It is stationary
You might want to check your motor mounts. On your Honda the one on the passenger side is the 1st one to check.
If it's broken you may be hearing the exhaust slapping on another part.
You can check it by having an assistant start the car, hold down the brake pedal, Put it into Drive, and then quickly step on/off the gas pedal.
If the mount is broken you'll see the engine lift up from the mount.
You want to be standing on the side of car so if your assistant's foot slips off the brake you won't get run over.

Thank you. I would also like to ask if its okay to buy aftermarket power steering pump for this honda?
I would. Your Civic is only 10 years old and already needs a new one. That isn't any testament to the quality of the original OEM one, (which will cost you around $200 more to replace)
You should make sure that the car is not moving when you put the car in reverse. Considering this, if you still hear the noise, then you may need to have the transmission checked by a pro.