Retrofit audi sat nav

[vrbob]

If i found a facelift S3 with the double din stereo is it a relatively simple job to retrofit the RNSE system like i did in my B6 A4?? if so is there a guide on here and also which satnav`s fit in the space is it the navigation plus or the rnse or both? I am assuming that if the single din stereo is fitted is a more difficuklt job as you woulkd have to fit the double din cage too.

Cheers