I once saw a guy with 9 12" Pyramid subs (Like these:
http://www.jjsaudio.com/items/d/53-1/Pyramid-6_5in-car-subwoofer.jpg ) sealed with separate chambers getting about 900rms in the back of a Jeep Cherokee. He did a 139.9 on an old AC mic. I did a 141.2 with two MTX 8000s sealed in the trunk of a 93 mirage 4 door getting 150rms each on the same mic at the same show.
Cone area and power mean very little with equipment as shitty as that. Sadly, I would say the old pyramids were a step above the pups... Install could help get a quick burp with a semi respectable number but I wouldn't bet much on it.