I am wanting to switch out my radio system so I can get my Sirius Stilleto 2 hooked up directly to the radio. I don't like using the FM transmitter, and I don't want to use it anymore...

My first question is, Will a monsoon radio work with the g6 that doesn't have the monsoon?

and Will the Aux work with the sirius radio player?

Or will I be better off going with aftermarket?

I dont think i can entirely answer your question because i dont know of how the computer in the G6 works.
Besides that you should be able to take it to a dealer and get a 2008+ monsoon radio installed that has a aux port and has XM build into it. (Since Sirius owns XM now i think it should be ok).
Yes the Aux will work with your Sirius unit you only need a cord.

No, the monsoon radio connects directly with a amp that is in the trunk. plus if you get a monsoon radio it may have XM ready. All you would need to do is switch service. Which is the same service now anyway.

about time i got an answer x) and i think I will just stick with a non-monsoon then. Looks like too much trouble to deal with getting it monsoon ready.

I know read the manual...however haven't got the car or the manual yet...

I getting an 05 G6 GT, this week...

can anyone tell me if the monsoon stereos are all 6 disc changers and I have are they all XM ready?

no... monsoon radios come either single disc, or 6 disc... and xm ready maybe. you'll just have to wait when you get your car?