It's the center one that goes over the stereo and vents. I don't know the part number and would hate to order a repair book just to figure it out. Thanks for any help.

http://www.doughalpern.com/main/wp-c...rior-lines.jpg

 

there are a few different part numbers for that piece, depending on what color / model you want -
Full Beige - BL4C-55-210-25
Full Gray - BL4C-55-210-61
Black sides, silver center panel (ES model) - BL8M-55-210D-00
Carbon sides, silver center (MP3 / early) Protege5 - BN5V-55-210-20
Carbon sides, silver center (Mazdaspeed / Late Protege5) - BP6B-55-210-25