The stock 5dbi omni antenna Alfa AWUS360h is coming is much better than the 9 dbi, which imho is crap. Google it to convince yourself!
Also take in consideration the antenna is used indoors, so the walls are attenuating the signal. Put the Alfa with the stock 5 dbi or 2bi antenna (depends on which one you're Alfa came with), on the windowsill. You will see a lot of improvement. Large in this case (9 dbi) is not as better as the small. Also, the cable that the 9 dbi antenna has is loosing the wifi signal. As long is the cable, the greater the loss.