Currently trying to find the appropriate USA SPEC Ipod Interface for my 2004 G35 Coupe w/ Bose. To my understanding, theres two options for this interface: one w/ a SAT radio tuner and one without.

I have a SAT button, but have no idea if I have the SAT tuner. Seeing how I have a SAT button, do I have the tuner? If I do, where is it?

Also, would you guys recommend the PAC over the USA-SPEC? I've compared them both and I don't use the SAT and I don't mind not having the navigation on the steering wheel. (I'm just shooting for reliability; I don't want a "hissing" noise when it's on stand-by like I've been reading about here on the forums.