Based on the Corsair web pages, It appears the fan included with your case is their Air Series AF120 LED model, with a max air flow of 52 CFM. For case ventilation fans, the pressure spec does not matter much. (See below for more details if you want.) In actual use, the front intake fan SHOULD have a dust filter in front of it, and that reduces the intake fan's air flow a little. So for your situation, using the Corsair fan as front filtered intake, and the new fan at 45 CFM rated air flow for exhaust, would make sense.
Some notes to help understand those fan specs. AIR FLOW is the MAX air flow that fan can deliver when running full speed and with NO items in the air flow path to restrict them. But when there are restrictions (dust filters are minor, finned coolers and rads are big restrictions) the flow is reduced, and the fan experiences a back-pressure to blow against. As the restrictions get bigger, the backpressure increases and the flow is reduced, until at some backpressure (and above) the fan cannot deliver any AIR FLOW. That max back-pressure is the "pressure" spec of the fan. Between those two cases, the graph of actual air flow versus back-pressure is VERY roughly a straight line that begins at max air flow for zero backpressure, and drops down to zero air flow at the max pressure spec. All that is done assuming the fan is operating at max speed; at lower speeds, the air flow and max pressure specs will both be lower.