ok i got a problem on my car that its dumping its boost when under acceleration only in 4th 5th and 6th and between 3k and 5k revs it dumps from 20psi to 10 - 12 psi then after 5k it goes back up to 20 psi. i have changed maf, and n75. so i have been told it might be dump valve fault. so if there is anyone in south Wales area ish and is willing for me to try their dv valve or standard valve. just for me to try as im spending money all over the shop trying to solve this. i have pluged code reader in and no codes.