Scirocco Central

Hello to all as a newbie on here........
Just returned to Scirocco ownership(was still in the brotherhood- Audi 8p S3)
This question probably being asked on here many times but had a quick look in the FAQ and couldn't find it.

Looked at a few before buying but ended up prioritising the pan roof/Candy white. Typically all the non proof examples had nav/PDC. The one I chose didn't! Not particularly bothered about PDC but would like to retrofit Nav. Gather the OEM unit is the RNS 315. Is this a good unit in that I can easily upgrade to latest Maps etc. One of the best aftermarket options i gather is the Kenwood 518? Like the sound of it but don't really want to spend near 900 notes on one....

Just use Waze? It's much better. Get an apple or android car play thing if u want to have it on the big screen.

I wouldn't bother with getting an outdated VAG navigation system

I just wanted an integrated system. With the 315 and updated does it afford a 7 figure postcode search facility?

So if my car has the shark fin on the roof does that mean I will not require an aftermarket GPS Antenna (a la Fakhrir)
Really not bothered about having an all singing all dancing unit with apple car play etc etc