[Msquared]

Some info on two questions in this thread: 1) location/existence of "amp" in the 1LE, and 2) the range of rear speaker frequency response. All of this info has been well documented in a big thread, Amp Location in 1LE?

1. Technically speaking, any speaker needs an amplifier of some sort to make sound. If there is nothing to generate the voltage and current required to drive speakers, you get no sound, and an amplifier is what does that. What we are really talking about is whether there is a separate amp in the trunk, vs an integrated amp (probably an op amp chip) in the tuner module. In the case of the 1LE, there is no separate amp in the car at all. The power comes directly from the tuner module, which is in the dash to the right of the glove box. The four channels of speaker-level signal come directly out of that module. Presumably this is a tip of the hat to track-oriented weight savings.
2. The rear side-panel speakers do not play full range. In the thread I cited, Ryephile says he verified this with frequency measurements. If he posted them somewhere, I don't think I've seen them. So I don't know if it's high-pass, low-pass, or some kind of more complicated curve. It's done in the tuner module and could very well be carried out in the digital domain, so who knows? Short knowing for a fact that you get full output down to 20hz, I would not tap the rear speaker signals for a sub (or anything else). I would tap the front speaker signals. You can physically cut and tap into the stock wiring to do this, or you can get a breakout harness from Gen5DIY.com like I did. It's really easy to run wires from the passenger footwell to the trunk: you just remove the passenger door sill and rear seat bottom.