loosing boost on aum gti

[Mark_AUM]

Hi there, first post on this from so go easy if i have made any mistakes.
Having some slight issues with my mk4 aum gti. When accelerating according to the boost gauge in the car, it spikes to around about 22psi and then comes back down to the 15psi that it should be according to the revo map that is on it. but then as you get further up the rev range it starts dropping off until it settles at about 5 psi. I have had all of the piping off, checked seals, checked hose clamps, checked for split pipes, intercooler etc etc. There are no fault codes showing up on diagnostics. The car is fitted with a milltek turbo back decat exhaust, bailey recirculating dump valve with forge cold side relocation kit, forge smic, forge turbo and intake pipes, and a neuspeed induction kit on it.
Any help with this problem would be much appreciated.

Thanks
Mark 

[davidgtrr34]

I had the same problem and it was the map sensor. I done the diode mod and this fixed it

[shaft69]

My AUM had same breather was split checked everything visually looked OK but bought boost leak tool off eBay found 3 hoses split. Fitted catch can now all good.