lack of boost

[jayeastanglia]

my t5 may have a problem or may be just how they are....noticed the dump valve(forge atmos type) made very little sound and found out the original dump valve on the turbo was still connected by its little vac pipe if i remove the original vac pipe and leave the forge one connected up i get 8psi of boost connect the original one up along with the forge i then get 12psi..sounds like to me somethings up with original dump valve as even putting a blank on the forge one i still get 12psi of boost..
Got a mbc already and a boost gauge..
any ideas why the lack of boost when i disconnect the original dump valve??

[Shadow]

it will run less boost with the vac line removed from the original recirc valve. the vac line to it also supplies pressure to it when on boost to help keep it (recirc valve) closed. to make the external valve louder you will have to remove the recirc valve and fit a planking plate.

[jayeastanglia]

ahh that explains why it runs less boost with vac pipe removed....

[Kingsford G]

Deffo need to blank the recirc one.

[jayeastanglia]

looks simlar to subaru wrx recir valve as well..