If it has the same connector type rp-sma...ie it will physically connect. There are 2 common types used and a couple more. You would have to specify the asus antenna to know.
How much different you get is hard to say. The simple math says you will get more than 2 times the signal strength. That does not mean a lot since the antenna gain is also has a impact on the radio ability to transmit and receive. It should give you some increase though.