How do you add a sub to the 6 disc radio?

[etcsjoe690]

Just bought an '05 STi, (woohoo!) and I know that there's an option for a subwoofer under the passenger seat. I didn't buy it because I have a nice JL W6 and Excelon amp to drive it that I plan to mount in the trunk. My question is, where is the pre-amp level output that the dealer would have connected to the otional factory sub? Or would they just split off of a speaker level out and use some kind of speaker to line-level adapter?

[Just Be]

The settings are on the factory sub unit. Two knobs.

[etcsjoe690]

Knobs? I meant to ask,- where can I fund the wires that the dealer would have connected to the subwoofer,...to feed it a signal. I want to extend those wires back to the trunk to feed my own sub amp. Sorry if my first post wasn't clear. And does anyone have a suggestion for routing power (probably 4 guage) to the trunk? Thanks!

[NewWRX]

I'm under the impression that the subs are actually hooked up like regular speakers, not via preamp outputs, your best bet is their is a connector that splits speaker wires into preamp out puts, that connects to RCA cables that go to the amp. You can ask any stereo shop or radio shack for it. As for the guage wire, that all depends on how much wattage the amps is gonna pull. 0-2 guage is usually good for 1000 watts so 4 would be good for 600-800 watts. Be sure that you get a capicator becasue the factory alternator and battery ain't great and you don't want to blow anything.