Why is the coupling off the outlet of the turbo to the pipe reduced in side. Is it a restricter or something or does it regulate back pressure from the turbo?

Good question because the Forge pipe has no such restriction.  I would like to know this too.

Pretty sure if you look into the turbo the diameter is the same size as the restriction you think you have!

So it's not a restriction

Haha, 'restriction' is the most poorly understood word in tuning, manufacturers do not 'restrict' their engines because to do so would reduce fuel efficiency and increase emissions.

That is true there is no restriction as such on the original pipe.  But then why is the Forge one totally open at the end and does this effect anything?. :

 

http://www.forgemotorsport.co.uk/Fluorosilicone_Turbo_Hose_for_SEAT_Ibiza_130_Diesel_and_Skoda_Fabia_VRS--product--274.html

I've binned it off now just put 60mm silicone hose over the top. Just intreeged me is all

Haha, 'restriction' is the most poorly understood word in tuning, manufacturers do not 'restrict' their engines because to do so would reduce fuel efficiency and increase emissions.

You've misunderstood me mate. I ment a restriction on the air flowing through it as if to keep a certain amount of back pressure to the turbo or something. Coskev was right anyway