Slight boost loss and change in turbo noise, cupra T 180

[Dissimulate]

Have noticed since i got my 03 cupra t 180 last year that sometimes i get a noticeable change in performance.
Since getting the car i have replaced my standard airbox with a carbon BMC induction kit and my standard DV with a 007p, i did have a splitR on for a while which i though might be causing the problem but still getting now and is becoming increasingly more noticable.

What happens, basically i can be boosting along nicely, hearing the lovely *woosh and chuff" thought my induction kit, hitting power where theres meant to be power.
Then, if i slow down or stop then pull off again it can change to a *whistle and a psss* (forgive my noise descriptions) and a lack of power. Can hardly hear any air being sucking though the air filter and a very lazy sigh when it dumps.

I've had suggestions ranging from problems with DV (which i bought brand new, but noticed the problem with other DVs too)
Un specific boost leak, meaning i would have to check all turbo and boost pipes.
MAF censor.

It seems its going to be a case of trial and error to find whats causing the problem, but does anyone have any more definitive then can suggest? would possibly save me a complete fart on and maybe a be of cash.

cheers

 

[nd-photo.nl]

Im putting my money on a MAF sensor failure. The BMC is oiled right? Try to avoid an oily filter as this will damage the MAF sensor. Uncouple the MAF sensor and go for a drive. Also it would help to get your car scanned with vagcom and see what that pops up

gl!

 

[Dissimulate]

had the car scanned not so long back before i had my water pump replaced and nothing came up.
will try unplugging the MAF once ive got my random indicator thing sorted first (few threads below this)

 

[RDS1972]

I've just sold my BMC oiled panel filter, as after using it for a while my MAF has apparently started doing the same thing.
On a rolling road day I hit a lower figure with the MAF connected than disconnected.
I've since added a dry filter, and cleaned the MAF. It's better, but still laggy and gutless from cold so now looking at the issue again.

 

[Dissimulate]

Ive only recently put the BMC on, before then was just a generic cone filter with breather pipe, its been doing it for ages, might try disconnecting to see if theres any difference but i just have this feeling that i have a bit of a boost leak from somewhere.