This is what I did with my FR,
I will add all the part numbers later when I am back at work,
Taking the front grille out of the dash is easy just clipped in so just use trim tool and remove, you will see a pre marked part you can pull out which will give you the space needed for new speaker,
Next I wanted to use my old 18" space saver wheel from my mk2 hence that is fitted with new sub,
You can use the foam tool kit holder which you will need to buy the correct one from seat or if you are using a 18" wheel you don't need anything apart from the longer screw in the middle again will post part number later
Next quite simple you need to run some good speak cable from the sub up the left hand side of the car into the glove box, you can do right by taking the trims out which don't take long but the only thing I would say is the trim that sits next to the carpet in the passenger door is a bitch to refit!
This trim is very easy to remove and refit
Remove this trim to feed the cables into the space behind the glove box
You will need the removal tools to just the nav unit out which you can buy pretty much anywhere
So with your wires run from the back to the front you now need to run two speaker wires to the front speaker, I did use a rod wire tool to feed the cable to the centre again very easy job to do,
Now this is where it maybe different from car to car, the quad connector on the back of the nav unit on mine already had the extra wires in??? ( I was following the Spanish
guide )
So I decided to take the pins out and see what stopped working, the sub pins on mine (which has high nav) went the front door speakers? and the centre speaker pins went to the front tweeters in the a pillar trims?
So I left it at this point and wanted to find a wiring diagram before I connected anything, I cant find the print out that I was given but the wires went to the same place?
so knowing this I connected the sub and front speaker by soldering them the wires just as they come out of the quad connector
its up to you
how to connect the wires there but did solder mine as I wanted it right,
Turned radio on and all worked fine and sounds great, yeah don't get me wrong its not going to sound the same as some one with two 12" subs in the boot but for a standard fit speaker system it does sound pretty good to me, if anyone lives in the Hereford area you are welcome to come and hear mine before you fit yours just let me know,
as I have said I have not yet been able to code the seat sound option into my car as I don't know which bit or byte to code I have sent a channel map to ross tech and they are getting round to sorting it, I do remember there was an option to code it in my
mk2 leon so hope they will be able to sort so I get the sub level option on the dash
Hope this helps if you want to ask me anything then carry on!