I have an RB30 with a GT3540, Synapse 50mm W/G, G4 Link, Mac Valve and Greddy copy FF plenum.Gradually building up boost currently at 20psi will settle on 25 - 28 finally. My tuner claims to have trouble getting the boost above 20 although i can't see why. I have bought a stronger W/G spring but figured that it should have been possible to acheive the target just on the Mac/Link alone. I will probably go to another tuner who should be able to sort it out but meanwhile there are a couple of questions to which i have been unable to find the answer.
There is a manifold coming off the FF plenum with hoses going to the Map sensor and boost gauge, W/G, Mac Valve, Bov, FPR I think that's about it.
But everything I read on connecting the W/G and ebc say to take the feed from a non vacuum source before the T/B ideally a nipple off the compressor housing. Why is that?
1. I can see that coming off the compressor housing would give the actual boost the turbo is making but isn't the pressure in the plenum of more interest?
2. And why a non vacuum source? Will the vacuum in the plenum under off boost conditions cause harm to the W/G or Mac valve?
(and don't ask why I need so much boost - that's a whole other story that we are working on!)