Regarding the options available in Sweden.
There's a few of us that have tried the JB1 with no bolt-ons and with bolt-ons (downpipe, intercooler).
A jb1 Cupra is rather quick 100-200 in the low 11s depending on equipment. Add a downpipe and you're looking at mid 10s 100-200. As the jb4 interferes with more connections and the
reviews from the us states more power I guess a jb4 cupra with dp will be looking at high 9s 100-200.
The limiting factor is stock intercooler. Intake Temps rises and at around 180 you'll get a loss in acceleration. Although it's noticeable only when looking in the logs and comparing every 10km/h split time. With another intercooler you're gaining ca 1sek 200-230 vs stock cooler.
I won't recommend any tuner but I'd read through forums and Facebookgruops... there's one tuner that's bashing themselves for being the best but for some reason never quite accomplish with the performance in the real word (outside the Internet).. then there's more humble tuners with a low profile but still need to proof themselves..
I've tried JB1 with and without downpipe but finally this summer ordered software from North America as I wanted something from a big reputable tuner with proven gains rather than "facebook fanboy claims".. the results are astonishing and my car is faster 100-200 with just a downpipe, dsg tune and stage 2 software than a full bolt-on Stertman Cupra (most definitely lighter than mine aswell as I've every options available in my car).
Within a few weeks I'll add a forge intercooler and cts turbo inlet pipe. In the beginning of may there will be a new event at björkvik and I'll make new performance logs as well as some movies ala gt board.com
I think it's worth reading the comments for this video..
Garaget | Golf 6 R Stertman Motorsport steg 2, 5 vs Cupra 5f Jb1 Fbo
http://www.garaget.org/video/152229