Airport extreme speeds?

We have been converted to everything Apple. I am on a new, 2mo.old Mac-Book Pro 15" I-7 intel with 8mb-ram, so good bells and whistles. House is running an Airport-Extreme less than 6mo old. I have Cox Business package, which usually runs at ~20ish mb download. (checked on Imac hardwired).
Here is my Question; laptop only gets ~6 to 8mb download speed I thought that the airport extreme ran much faster than this?? Do we have something configured wrong, or is that max speed? laptop has 'max' signal.
Sorry for going long.
Thanks Dave

I would re check your configuration I get 11.4 on a 11.4Mbps download both wired and wireless off of the AEBS thats less than a month old (should be same model).