Are you absolutely sure that it's a deflector problem and not a weather strip problem on the door? I get a good amount of water on my driver's side after a downpour, and of course there's no deflector on the driver's side. My weather strip at the top of my door is torn, so I know that's where it comes in. I don't have carpet anymore, and my GP is my junker, so I just throw a towel down to absorb all the rain.
When it's not raining, close the doors and pour some water over where the deflector is installed. If you see water leaking in, then it's the deflector. If it's not, try pouring water around door, and see if it comes in.