You must plug the antenna from the radio into the the mod and then to the outside antenna. All power hook ups will be under the dash, to the fuse box. Not too tough. Just READ the instructions, and take your time. One other thing, that mod, gets really hot. Becareful where you place it.
I have XM. I use a Skyfi in my car and in my home stereo. Since I have never used Sirius I have nothing to compare it to, but I am very pleased with XM. It satisfies my needs in music and information. Plus it sounds soooooooo much better then local FM.