Retro Fitting a subwoof into a 300tdi..How easy?

Has anyone of the bright sparks on here done this, and if so is it easy/hard/or bloody hard? Would love an assist Cheers. J

Yes done it. 200 watt Amp sits under the passanger seat and sub in a box on the boot floor.

I have an existing sub in the back door so I picked up the audio and switching feed from that, the main 12v power feed is from the battery with 8mm or 10 mm fused cable as normal.

The switch feed for the new amp was picked up from the door amp via a two way mini switch so that the switching 12v can be isolated from the from the door amp and diverted to the new amp. When I have to remove the sub in a box for some boot space I can fick the switch to restore the 12v the door amp back for normal operation and isolating the new amp.

Audio feed is just 'T' into the existing with a soldered and taped connection.
The new cables are run from the back door following existing wiring then under the carpet to the location on the new amp.

There are three circuits to the rear sub. 12+v amp power taken from the head unit supply, (light green/orange wire at the amp, also a local earth wire which is black at the amp).
The 12+v amp switching wire (purple/yellow at the amp).
The audio signal cable (black & white wires in a screened cable).

IF u don't have a door amp then your head unit must the connections/outputs for a sub be for u start.