Sub RMS power handling...?

I have 1 of these (http://www.sonicelectronix.com/pictures_new.php?from_sonic&id=6981&picture_id=114605) that I'm going to put in my buddy's truck for him. I have it wired like this (http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/1DVC_4-ohm_mono.jpg) for a 2 ohm load on the amp.

What I'm confused about is that this page (http://www.sonicelectronix.com/item_6981_Diamond-Audio-TDX10D4.html) says that the max RMS power handling is 800W but, as you could see in the top link, it says 500W right on the sub. Is that 500W per coil or something? I would just disregard the page as a typo but I've seen it on a couple different pages. Why does it say 500W on the side of the sub if the thing can really handle 800W RMS?

I would guess 500 is the RMS and 800 in Max. There are painfully few regulations reqarding rating of car audio equipment, so take them with a grain of salt. I would use the RMS rating stated on the sub, it is probably more realistic.