upgrade 2004 GTP sound system

I want to determine if the stock radio on my 2004 GTP can drive subwoofers and if I can provide aux input. Does anyone know if it does or how to remove it to see if it does?

I too have just purchased a 04 GTP Comp G. I talked to my local audio shop and it turns out they now have 2 little devices to make this a snap. My current head unit has built in XM and tied into my HUD and steering wheel controls. One device taps into a speaker lead and converts the signal to line level. Then you don't have to worry about head unit pre-outs. The second device also taps into a speaker lead. If any power what-so-ever goes to the speaker the device triggers the remote on for your amp. My stereo guy says it costs about $40 for the two little devices. Hope that helps!!