leon cupra mk1 1.8t 180 auq loosing power

[luppy]

Hi everyone, new to Lc's.
Having a few probs with my cupra.
Apparently my car has been mapped and larger i/c and few other mods.
i must admit it is quick. But it seems to loose boost like it runs out of power until you change up then does it in every gear. Sounds like its shhhhh alot. Has a forge d/v. It has the standard diverter valve still on it is that normal? I'll take some pics of my engine 2mo. And see if you guys spot any probs. How is the best way to check for leaks? I had it plugged in and its got a code p0411 sais?
Thanks for your help and sorry for all the questions

 

[Nrlc180]

I'm having exact same problems on same car as yours did u find solution

 

[luppy]

No still doing it. I think it might be on the pancake pipe by intercooler as looks a bit oily on the silicone pipe joint. Might get a chance to have a look at some point