As you know from previous threads ive been chasing boost leaks and power loss.

Pcv changed - slight improvement running

Diverter valve changed - no difference

Full service - no difference

Unplugged maf - 20% better but still down

New o-rings from turbo to intercooler ( 3 ) -

Much much better and less noise

Unplug maf after o-rings- even better still

Conclusion !

Car has been poorly maintained, boost leak was obviously o-rings but the ones i removed were green so had been changed at some point, and faulty maf as unplugged it runs better power than plugged in. 

Next job is replace o- rings on throttle body side of intercooler and replace maf, i am assuming that with maf unplugged it is running a base setting, that setting is still quicker than plugged in so should have better performance when replaced.

Yup, new genuine maf will be much better.

Dont get a pattern one... youl just end up buying an oem one is 3-6months time anyway.