Is it possible that by fitting a VTA dump valve my car feels a bit slower?

I am nearly certian that this thing has made me loose some ponies! Its the after gearchange pickup that seems to have suffered.????

Its a bailey DV12 on a Newage 03 STI.

Should i get a better recirculating version

 

If you have any leaks when its fitted you will be loosing boost pressure. This can be leaks caused by the valve not sealing properly due to it being faulty or through incorrectly fitted vacuum pipe or not replacing the gasket on the intercooler mounting. It doesn't take a big leak to loose boost pressure.

A correctly working VTA dump valve wont make the car slower. The standard recirc will happily cope with quite a lot of modding before it needs to be replaced.

You may find this an interesting post
https://www.scoobynet.com/drivetrain...ml#post4056125