Currently i have 1 JL10W3 V3 in my jetta. This weekend i am going to be building a box to place the sub in the lefthand side pocket of the trunk.

Later on i would like to build another box and add another w3 on the opposite side of the trunk for some extra kick. From what i remember from being heavy into car audio a while back, running subs facing each other is ok as long as they are wired in phase with each other. IE. one pushes while the other pulls. Is there any ill effects of this? Or should i just upgrade to a w6 with more power and keep one to the side?

 

If you invert one sub you wouldn't have to phase (correct?). If you want bump and want to stay with JL, skip the W6 and get a 10 W7 in a ported box, it'll probably eat both, and be +/- 1.8 cuft, pretty small still.

 

Also how do you wire up subs in phase? On my deck there was a 180-on/off. Can you have four subs with two in phase etc?

 

there is acoustical and electrical phase, electrical is simply reversing the wires.
acoustical phase you wont know until you try it, if you have really bad cancellation or other funky unexpected sounds, reverse the wiring on one of the subs.

What you're talking about however is usually only worried about if the subs are in the same enclosure or within a few inches from each other.
on the other corner of the trunk, you'll be fine.

 

so, to wire them "in phase" in the same box all you have to do is wire the + to the - and - to the +?

 

I guess it's the same for firing away from eachother? If that's the case I can fit 4 sealed 12's in my trunk .

 

That would be reversing the polarity of the speaker.

I prefer to use polarity when dealing with electrical connections and phase when dealing with acoustical issues. It helps avoid confusion..

 

LoL...I like it!

 

^ lol, dammit. That's what I get for talking and posting at the same time

As for the original question - you shouldn't have any problems with cancellation with a woofer on each side of the trunk.

 

so if you reverse the wires it will change the polarity or what?