The stock intercooler used in the Cupra is really not bad, it is quite good in fact.
Mounting a bigger downpipe with a racecat brings much more because the heat isn't stowed anymore behind the turbo and the turbo itself will thank you for that.
The stock intercooler works very well up to 400 Ps and even more.
Check this out here, they achieve 480PS on a Golf7R (exactly same engine as the Cupra) with the stock intercooler but it is in German language. Runs like hell and just look at this video where you can see what they modified and all this with the stock intercooler which really performs well.
http://www.hgp-turbo.de/vw-golf-vii-r.html
Video:
https://www.youtube.com/watch?v=tVuUhdWey28