What exactly did you install ? speaker size? Box size? I don't even know where to start... I used to drive a truck with a 12'' shallow mount behind my seat it sounded pretty good.
sounds like you did this,
can you confirm, whether above is accurate diagram? especially powering LC2i?, I would like to avoid running 2 power wires from battery if possible. Is it possible to tap power from amp to LC2i, not even sure if there are amps that allow you to do this. Also, do you have any issues with amp staying/turning on, for example when you lock/unlock car?
Also, you only mentioned that you tapped left rear speaker, but I'm assuming you need to tap both speakers? TIA, I also have 1.5t sport and this definitely helps.
The power side of this is accurate. You could
use the positive lead going to the amp as long as the wire and fuse support the (rather small) increased power draw. You'd still want an additional fuse for safety, not doing so would be very unsafe. Best practice is to run a second cable.
I assumed that the left and right speaker get the same bass output from the head unit so I only tapped the left one. Thinking about it I should add the right speaker in case a track has a bass line that has separate left/right tracks. That would be strange but I'd rather do it to make sure I'm getting everything.
I've update my original post but I'll add it here too. ANC did activate a couple times during my drive, it wasn't awful but I'll probably end up unplugging it.
With the LC2i I have no issues with the amp turning off or on since it features GTO (great turn on). This detects a signal from the factory speaker I tapped & turns on the LC2i which then turns on the amp through its remote out line. This way you don't have to run another line up the the fuse box. This feature is another reason the LC2i is a must.