I would leave the two intake fans in place and add another fan as exhaust.
2 Exhaust (one being power supply) and one intake will cause dust to be sucked into your CD/DVD drive ,USB ports, card reader etc... Anywhere air can be sucked in dust will also be sucked in.
The A20 is an ok cooler,a little better than the stock fan but quieter. So don't expect drastic temperature changes.