Choose ones with air on the bottom part, avoid ones with air only in the top.
I agree with this wholehaertedly.
Also, be carefull of the air you are getting installed.
Seeing as how you are in Texas, I would recommend that you have the "summer" air installed.
In your temperatures the "winter" air could cause some pressure related problems at highway speeds.
Always pays to know your air ( oh, and stay away from that imported air, it ain't worth the extra $$).
RTR