There are a bunch of write ups on it, detailing how to take it apart and replace. Took me about 45 minutes mostly because of these PITA clips. I put a 6.5" kicker sub. I had to shave some plastic inside but nothing detrimental. You can get pyramids, or the Quadratec replacement sub but I am happy with my kicker. Someday I will replace the factory amp with an amp to power the sub and all my speakers.
'when people look like ants -- Pull. when the ants look like people -- too late'
'if at first you do not succeed, skydiving is not for you'