Premier Internet. Can't get past 32 Mbps barrier.

Just got my Docsys 3 modem installed to go along with my newly improved Premier account.  My old modem peaked at 20 Mbps so any increase is a good thing.  After talking to a Cox rep on the phone, we were able to get the new one installed correctly after the "Automatic Installation" failed.  Now I'm doing better at 32 Mbps.  I've check with Speedtest.com and come up with 32 Mbps.  Cox' speed check also comes in at 32 Mbps.  In fact, it always comes in at 32 Mbps.  Chatted with a Cox rep online, he told me how to prep the set up to get the maximum bandwidth.  I powered everything down, connected the modem to the computer directly, Plugged the modem back on, waited for 2 solid lights, went to my computer and started it, finagled the network settings, and got back online.  At 32 Mbps. 

It's always 32 Mbps.  Why?  Why can't I get those oh so glorious speeds of 40, 50 and more, speeds that I keep seeing in the forums?