What did you guys use as the remote wire... IF you left the stock headunit in and added another amplifier?

 

Depends on what type of stereo you have and what year/model that your car is.
You may have amplifiers under the rear seat (passenger side) which you could tap into. There may be a blue wire near your stock sub-woofer in the center of your rear deck which you can tap into as well.

 

It is a 99 3.2 TL