Exhaust diameter?

Hi,
I need a new exhaust, I live in Norway so my choices are limited.
Importing or bying from uk/eu is out of the question as taxes makes it stupid expensive.
Basically I have 2 choices:
https://www.xtremecar.no/simons-effektanlegg-029-h5.html
or
https://www.xtremecar.no/simons-effektanlegg-029-h.html

I have a 1983 1.6 GL all original atm.
(I dont need a sports exhaust but an original is almost the same price so I thought why not.)
What makes me unsure is the pipe diameter.

So my question is… is it 63.5mm or 50.8mm that will fit my original downpipe?
(I've searched this forum and the web in general but it's not made me certain in what to go for.)
If someone has any idea I will realy appreciate the answere.

Thank you.  

I've messured my original exhaust tube and it's 40.5mm on the outside diameter so 50.8mm is the closest one,
still not sure since they are far appart in size.

I might just go for that… gahwd… I'm so unsure about this.  

50mm will do you fine, its stock size for the mk2 gti. anything bigger is overkill

if your not changing the manifold, the "sports exhaust will probably make hardly ant extra power, just more noise.

Ok thanks.
I am not looking for power, just the cheapest way to
fix it, strangely enough this package with all the bit's
in it is the same price as a standard when you add all the bits up, or cheaper, depends where you get it from.

Yeah I asked the seller (company) and he said both would fit.

Fun fact:
After contacting him with my question I went to order
and he had upped the price with about 60 pounds!  
I Ordered anyway and after recieving my money he contacted
me and said they do not make them anymore and that he can not get hold of them anywhere.
A real serious buisness right there.
(I got my money back though after 4 days)

I've since managed to source the same exhaust in Sweden but it's a long drive.  
(Apparantly they make this exhaust for swede's still.)

You guys in the UK should be smiling all day with the
massive selection of parts and the ease it is to get hold of them… I would.  

There are many uk vendors, but most just get there parts from small number of distributors, they dont know if the distributor have the parts when you order. Few have them in stock.
So it maybe an illusion that we have such a choice.

How ever the best old vw's hide in Sweden (my own car is a Swedish inport.
All we have in the UK are a few late rust buckets!

I don't like doing Exhausts…
I usually farm this out to a Mom & Pop Exhaust shop.
They can bend, weld and be done with it for what I could buy one for and mount it.    It is very easy to increase the diameters of the pipe…

About the only thing I do is to swap manifold from 4-1 to 4-2 or a header… I then drive it noisily (sounds baddass) to the mom & pop shop to have them weld it up….

On headers don't forget to include a flex pipe to allow for torque shift of the engine.  Some headers do and some don't have a flex….

and if you do decide to do it yourself, use the new style Band Muffler clamps, they are about the easiest way to connect pipes and clamp so the pipe doesn't get collapsed making it easier to remove it later…

Thanks for the tips, I will look into getting a flex pipe,
don't know if I can get hold of such nice and hightech
clamps way out here in the wilderness.  

Yeah my car is a swedish import aswell, don't know
what they do with their cars there but they last longer.
It's just across the border for me so it realy shouldn't
be that much of a difference.
Less salt on the roads I've heard, donno.

Thanks.