Been thinking about a boost controller for a while but couldn't make up my mind which way to go, electronic expensive or cheap manual. The cheap manual ones work on a ball and spring and although I have heard good reports on them I didn't like the way they operate by suppressing the pressure to the wastegate rather than bleeding it off as the standard set up. I had tried to just bypass the solenoid but that gave me too much boost and spiky too, so I thought if I bought an adjustable valve and just bled a bit more off than the solenoid does I would get as much boost as I wanted. As standard with the solenoid shut and no air bleeding off then the wastegate opens at 3 to 5 psi, solenoid open and you get 7 psi. This is all confirmed with my boost guage, which although is only a r32gtr one, seems to read right.
So I bought one of these off ebay for £18
I had to change one of the male connectors to the bottom and blank off the hole. I then modified the original solenoid bracket and mounted the new valve to it.
I first tried with a full turn out and that gave me about 10 or 11psi, so screwed it in to just over half a turn out and that gave me about 8 and seems to be nice and steady with no spikes or anything.
Very pleased with it, nice and cheap and only took an afternoon pottering to fit.