Mazda 6 2003 stereo

Ok for all of you stereo guru's I have a mazda 6 2003 model and it has the bose stereo in it already and I'm wanting to put some 12's and a amp in it to get a little more bump lol. What all has to be done to put one it, I know that bose has the amp with most their speakers and my car has the factory 10 that I assume will have to be bypassed? Any hlep will be more than appreciated. Also how hard is it to do, is it worth my trouble or not?

Ok first off. Get the wiring you will need. depending on what wattage the amp is will determine what gauge wire you will need.I.E 8ga, 4ga etc. Also pick up a PAC_SNI35 hi/low level convertor. Locate the factory sub. Determine what wires coming from it are positive and negative. You can hook up the hi/low level convertor to those wires. That will be the easiest way to hook it up.