Everyone with modified Monsoon systems in here...

I'm looking to get the correct adapters and add a driver's side subthump box and possibly a passenger's side one too. I'm going to keep the stock head unit (or I was planning on it).

But to turn the volume to the max, it seems like the stock speakers would blow unless you could somehow put a crossover on them.

How can I handle that?

adjust the amp

And how exactly do I adjust the Monsoon amp?

open trash...insert stock monsoon amp...purchase aftermarket amp.....install and there u go:p :D

The monsoon amp can not be adjusted. You will need to adjust the amp of the aftermarket amp that you use for the aftermarket subs that you install.

To complete this you will need a LOC (Line Output Converter) to send an RCA line level signal from the head unit to the aftermarket amplifier. You'll need the aftermarket amplifier and you'l need the aftermarket subs. That along with some cabling is all you'll really need.