BPD - If you insist on using Infinity component speakers or co-axial speakers, I would suggest these..
Infinity Perfect 6.1 (perfect61) 6-1/2" Component Systems Car Speakers Car Audio and Video - Sonic Electronix With a 4-channel amp (to run you tweets and speakers together)
Infinity Reference 475a Multi-channel Amps Car Amplifiers Car Audio and Video - Sonic Electronix I have heard a lot of Infinity speakers and I personally think they are more of a mid-range speaker compared to most other brands. Atleast spend the extra $100 for some better Infinity's if anything. The main problem with most of Infinity's components are that they are eith 2 or 3 ohm and most of your head units are 4ohm. So if you plan to try to use your H/U alone to power these then you are gonna be in for a big disappointment. Your speakers will end up being under powered with heavy distortion at low volume ranges. Thats why David and I both keep suggesting the amp as well.
Side note..... yes the antenna wire is for "power antenna." If your talking about an antenna adapter thats to be able to run your aftermarket H/U to recieve radio in the car. Most new cars don't even need an aftermarket antenna adapter anymore. Not sure if the Z does or not.